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UNIVERSITY OF ILLINOIS 


CHEMISTRY DEPARTMENT 


ARTHUR WILLIAM PALMER 


MEMORIAL LIBRARY 


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A TREATISE ON CHEMISTRY. 


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A 


TREATISE ON CHEMISTRY 


BY 


Sir H. E. ROSCOE F.R.S. anp C. SCHORLEMMER FE-.RS. 


VOLUME III 
THE CHEMISTRY OF THE HYDROCARBONS AND THEIR DERIVATIVES, 


OR 


ORGANIC CHEMISTRY 
PART V 


“Chymia, alias Alchemia et Spagirica, est ars corpora vel mixta, vel composita, 
vel aggregata etiam in principia sua resolvendi, aut ex principiis in talia 
combinandi.”—Stau, 1723. 


ne- YF 


NEW YORK 
ue APPLETON AND COMPANY 
1889 


Digitized by the Internet Archive 
in 2021 with funding from ° 
University of Illinois Urbana-Champaign Alternates 


https://archive.org/details/treatiseonchemis35rosc 


PREFACE TO VOL III, PART V. 


THe Fifth Part of the Treatise on Organic Chemistry 
contains a description of the Benzene-Hydrocarbons and their 
Derivatives with eight and more than eight atoms of Carbon, 
and concludes with the group of the Terpenes and Camphors, 
including Indiarubber and Guttapercha. Like the preceding 
parts it forms a chapter in itself. The authors are much 
indebted to Dr. A. Harden for the assistance which he has 
given them in passing this volume through the press. 


C. 8. 


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eh, aa 
‘ 


. 
mon 





CONTENTS. 


PAGE 

EIR DOU AWE et at. OP a ee ge eS 
earn OU eier Mean ries ein) Pin iw? a ee ee Lege aD 
Styrolyl Compounds a PAG Shee oe ae ee ee abe Nt aT, 
Phenylacetyl Compounds ; ie © hes Cen O 
Halogen Substitution Products of Pheevierctia pen eek Aa 
PaLPO DU tIROLO LAL a ch ae te ec te aS 
Amidophenylacetic Acids MC ine ae Bie 6 tk ke a Pee 
Hydrophenylacetic Acids PeeWee Toe oe Cana ce ate) i ee eae 
Dihydroxyphenylacetice Acids - A key Piatt he eo Ee aecoe 
Styrolene, Ethenylbenzene, or Bien yiiisians une nth mira Goel ae 
Supstsiiom crouneta of Btyrolene «=. =. 9. . kl lt he 
Phenylglycolyl Compounds .. de, ae eV pane Mf: 
' Amygdalin or Glucopheny ikparcxranctoniteil ae Pied Bee gs eet et ae 
Aromatic Substitution Products of Mandelic Acid . . . |. . O51 
PemervineatowUnnipenmae: OS i he i ge gL. Vo ee Be 
BPO T INCLU UINA ONG Te! a oe 8 ek he ee et A. then oe 
Benzoyimethylene Compounds . . . . . . « « « 68 
SIMEmtmee ET SOUT rey ee ee a ae hb ik ade le 
Reema T EIN VIC ONIDOUDCR Ey — 3 a ae es gs ow ee Oe 
Isatin. . Seg a. pc ek el eee 
Pater benearie or Pisayincaeylans WO rae ene 44 96 pL 
CUMENE GROUP ‘ SR Care re) Ja nee eee ered oi? YY 
The Miesinethy  benizeniss ae se gk Shee 
Halogen Substitution Products of the mriiteah yl bonsestes ay ote wa et ty: 
Nitrotrimethylbenzenes . I a a ree Re oti 
Trimethylbenzenesul phonic Aerie a ot am hy ear Mk Ate 1% he 
Prioetnviliydroxybenzenes./".. 8.) Ue ee 
Trimethyidinydroxybenzenes,... ", y-. ew, tw lw 
Amidotrimethylbenzenes NEAR tary a eg. | Ae loa ee an 
Mesityl Compounds. tek), aretha Ot eine ag | eee 
Dimethylbenzenecarboxylic iia ‘ Un lat cal sce 
Substitution Products of the Dimnethylberememrtaxyiia *Keldé es Vee 
Dimethylhydroxybenzenecarboxylic Acids. . . . . ... 180 


Dimethyldihydroxylbenzenecarboxylic Acids . . . . .  . 181 


vill CONTENTS. 


PAGE 
CUMENE GrouPp—continwed 
Mesitene Compounds. ag oe ee ce 
Pseudocumyiene Compounds’, © . °° © Vi) a ee ee ee 
Methylbenzenedicarboxylic Acids. ~~...) © fae 
Methylhydroxybenzenedicarboxylic Acids . . . . . . . 186 
Mesiteny! Compounds =... . «a> 6 Sie ee 
Benzenetricarboxylic Acids .. cite. (ed og Sees 
Hydroxylbenzene- Aldetyaonicarniecrne eae oT ey A ite eee 
Hydrobenzenetricarboxylic Acids .°* <<) 02 cw) e000 ee 
Phiorogincinoltricarboxylic Acid}... 9) ">. 9 ee 
The Methylethylbenzenes:* 22° 2) 0 St 
Tolylmethylketones. 4 haa 
Ethylbenzenecarboxylic sey or Bhylphenylformi INSBE hese ee 
Methylphenylacetic Acids . . lee APPA eet ae COTS hh oe 
Methylstyrolene or Tolylethylene.. <= 2 (2) 9 9 Sas 
Methylphenyl-Hydroxyacetic Acids’ <>. 0) 40 oe ee es 
Ketonic Acids” 5° - sp. ee i ec cot 
Homophthalic Acids Be Gh ee Gi iy Aton Sie | epee mas aE 
Phthalidecarboxylic Acid’ >. - “2 — ee ee ey 
The Propylbenzenes ee ee ee ee PR eI 
The Phenylpropyl Alcohols. < ) =4. @. 9). (p )) 9 soe 
Ketones . . oo wi a i eee Re 
Phenylpropionyl Compoutiaa reer ces GC REor oy lee ye ye 
Iodohydrocinnamic Acids” . 4.3%" 0 3 92.62 | 3 Ce 
Hydroxyphenylpropionic Acids -. = 9. *. «3 ye 
Dihydroxyphenylpropionic Acids. 9. 3. 9). 5) 
Phenylhydroxypropionic Acids «2 jie) “Git 
Ketonic Acids .. oe AO Ne es ee i ae 
Phenylpropenyl Companies with. ogee bel tea g ih te) Ries 2 eee oc 
Phenyldihydroxypropionie Acids 90). 9 a ee ee 
Phenylpropylene .. 3 lace PE ORS One ee ea ee 
Phenylally] Compounds.) 5.0 8. ag 
Phenylacryl Compounds. . mhaeiuglt.< tos pane Ngee as ett Re 
Cinnamic Acid or 8-Phenylacrylic an SO Ns ae ae ae a eae 
Halogen Derivatives of Cinnamic Acid poe so, Bon i we ea ee 
Nitrocinnamic Acids nS Se A Mm Bey eS 
Amidocinnamic Acids” 7) co 3. eek a 
THE CARBOSTYRIL GROUP... vi Ny Sean oth Ns) ey oats ane 
Hydrazine Derivatives of Chace Aga so hae Uhrig her aE 
Atropic Acid, or a-Phenylacrylic Acid NG ee ae ie 
Phenylhydroxyaerylic Acids; =, =. 4) \, y/o) oa 
Hydroxyphenylacrylaldehyde ee eee ee TL EN ey ek 
Hydroxyphenylacrylic'Acids®, = .  ’t"_ 4 eed fa) ee 
Dihydroxyphenylacrylic Acids — <2) ul 0p pe 
Trihydroxyphenylacrylic Acids.” 5 00.5 cs en 
PHENYLPROPIOLIO GROUP 5 8 ey ee 
Substituted Indole.) co) 0; 00. is oe NG ee a oe a 
Indolcearboxylic Acid); 5-7 ea ps ae ee ee 
THE CYMENEGROUP ... Sel RET See Try, 


Trimethylbenzenecarboxylic Bede Pt | BO ee eee eens 


CONTENTS. ix 





PAGE 
Tur CYMENE Grovup—continued, 

Dimethylbenzenedicarboxylic Acids . . . .-. « « « 279 
Benzenetetracarboxylic Acids : : : ; : ; : . 280 
Dihydroxybenzenetetracarboxylic ‘Acids ‘ : : f : ; = 288 
The Dimethylethylbenzenes . ; ; , : 4 ; : PPes4 
Acids, C,y9H,,03 and Saat Fb ie eh Ned mes oaks te ee, ) eS OU 
The Diethylbenzenes. OPN we oy ad ae a ae eh 
MI ecVIDCDYLDeENZenes. =. ge zw ee ee ae os 287 
ree PUMOGS ee Me ies ee ew ol Me ge et ett ee B08 
irorginyoroxybenzois Acids. 6 ow ew, re a” ae 809 
Seproee propy lenz0ic Acids «=a 95. ew Sc ee eS es bat 810 
Tolylpropionic Acids Vy er A A eke Taek 
Dibasic Acids and their Tyerivdsivas ake ie be Bag iat eh 
Methylpropenylbenzene and its Derivatives a ne Un hetets eC eee eae 
OM MIAV DOD PONG Pen lawl er led.) dey Pouka If cei 8 QR eke 
Aleohols, Ketones. : : : : , : : ’ . . 3820 
Phenylbutyric Acids ee, Wile ag Rane: aie Mak Mit. tale eta 
OSU VI VOTOLY ler T Gr GIGe ce ey biel le Cake we | me ac Pe ek 
Ketonic Acids .°. . PPA ee Some oe 
Benzoylacetone and Pawar yi ays dricanite Ata Be are a ee Ra ies 
Dibasic Acids, CgH5.C,H,(CO,H), . ogy § XO BE cot Oo 
‘“Phenylbutylenes or Butenylbenzenes .  . . . =» '« \% «: 826 
Bee ViCTOLOR VT AGIOGM | CPM ok ire fe iw ta es) a on areas 
Hydroxyphenylerotonic Acids bet ee ee te ee Ok 
Rimyaroxey POCO YICYOUOMIG ACIGS oC 6k, te ge Ce) ele we OS 
EID COTURYDUGNVICROLOEIG AGIOS, * 4 ig wk we lw) ee) a ao Bae 
ere atti) eg A eee 8 a KU ale. Mog ae oh Med’ 9p! Yen BOO 
Pemree ai san eee eee bth kw) oe ks pi ea eee 
Ketonic Acids, C))H,O, . wee eon k os. et er on, ed ee 
Dibasic Acids, ‘C,,H,0, . Pe ee ee ee 
Hydrocarbons of the Formula, C, H, Cy “a ee ee ecen Wane a ee 
Indols ‘es aE ate es . 340 
Indolcarboxylie Acids ein Tots Chitjen Atoina cca yen eRe’ 
THE LAURENE GROUP... Gulecad (acer } Otho nga ta), Oe 
The Hydrocarbons of the Parmoin: OnE i, eb PA arae gr Se hea eee 
Pentamethylbenzene Sa te eT Pa ee 
POM Ob yiGleniy bGUZONG sc a te ee . 346 
Dimethylpropylbenzene . Sceg/s Mey ce chge et > “6 Rhee Reas HSE 
Methylbutylbenzenes or Bec eslnenss: a St Patents | 
The Pentylbenzenes. Phhibere: oC.) aes 
Hydrocarbons, C,,H,4, and ae Dertvations Ane fot Bak EAs ODS 
Hydroxy-Acids, C,,H,,0; Oe ee ere eS a ee ae ere 
Pw UPOE Pele Mara tia tee Sone ee See ee Beg) ee ee OU 
Cet CCR Es yl 9S Dey mane ep ems: © NP ye rr y ON bic] tee ety 5 
Diketones, C,,;H,,0, ole ge Ree. eee vet. Riot ota ae eee Be 
POG IO CRAIN case 20 at ck? ile eM eae Ties ty Sat vane ehy coe 
DE CRrAALD Ss Me? So ca", aye ame ie oes 81% by) into e ec Stubs wha haw, Dit G L 
Tribasic Acids .. tte, 6 Rn toa! OOM 
Acids of the Composition, Cul fe Hg. CO, H A Se Ne get 


Coumarin . 5 ; 2 A ’ : : : : . 068 


x CONTENTS. 


THE LAURENE Group—continued. 
Hydroxycoumarins . 
Acids, C,H;.C,H,.CO,H . 
Indol Derivatives containing Eleven foie of Caran 
MELLITENE GROUP 
Hydrocarbons, ©,,.H)., al hole Denratres 
Mellitic Acid 
Triethylbenzenes 
Dipropylbenzenes 
Amyltoluenes 
Isohexylbenzene 
Acids of the Formula ete a) 
Ketones and Ketonic Acids 
Dibasic Acids : 
Hydrocarbons, C,.H,,, and then Derivatin 
Acids of the Formula C,,H,4,0, 
Unsaturated Dibasic Acids : 
Hydrocarbons, C,,Hn-10, and their Tanase 
COMPOUNDS CONTAINING MORE THAN TWELVE ATOMS OF Chdaae 
Pipitzahoic Acid : 
Alcohols of the Formula C apy 
Hydrocarbons of the Formula C,, Hon -g 
Alcohols of the Formula C,Hn2-30 
GROUP OF THE TERPENES AND CAMPHORS . 
THE PINENE GROUP 
CAMPHENE GROUP 
Oxidation Products of enh: 
LIMONENE GROUP 
DIPENTENE GROUP . 
SYLVESTRENE GROUP 
TERPINOLENE GROUP . . . . b fon Fe 
TERPINENE GROUP . 
PHELLANDRENE GROUP . 
Compounds related to the Ommchar 
Isomerides of Borneol , 
Isomerides and Homologues of Genrer 
Sesquiterpenes and Sesquicamphors 
The Diterpenes . 
Acids of the Formula CopHy)0, 
Guaiacie Acid 
Polyterpenes 


INDEX 


PAGE 


- 362 


369 
379 
373 
373 
374 
381 
382 
382 
383 
383 
384 
386 
389 
389 
391 
393 
394 
397 
398 
402 
402 
408 
412 
417 
441 
450 
455 
464 
465 
466 
467 
469 
471 
474 
476 
479 
480 
483 
485 


501 


ORGANIC CHEMISTRY. 





ORGANIC CHEMISTRY, 


OR THE CHEMISTRY OF THE HYDROCARBONS AND THEIR 
DERIVATIVES. 


PART V. 


STYROLENE GROUP. 


ETHYLBENZENE, C,H,.C,H,. 


2274 This substance was first prepared by Fittig and Tollens 
by the action of sodium on a mixture of bromobenzene and 
ethyl bromide,’ and is also formed when ethylene is passed 
into a heated mixture of benzene and aluminium chloride,? and 
in small quantities, when benzene is heated to 100° with ethyl 
ether and zinc chloride.? It has likewise been obtained by a 
remarkable reaction from toluene, which on heating with alu- 
minium chloride in an open vessel yields a mixture of hydro- 
carbons consisting entirely of ethylbenzene and the three xylenes. 
These cannot be separated by fractional distillation, but their 
amounts can be determined by a method which is more fully 
described below.* In order to explain its formation, it may be as- 
sumed that the toluene is resolved into benzene and methylene, 
one portion of the latter combining with toluene to form the 
xylenes, while the remainder is polymerized to ethylene, which 
combines with the benzene with formation of ethylbenzene 
(Pt. IV. p. 202). 


1 Ann. Chem. Pharm, cxxxi. 310; Fittig and Konig, Jbid. cxliv. 277. 
2 Bahlson, Bull. Soc. Chim. xxxi. 540. 

3 Bahlson, ¢bid. xxxii. 618. 

4 Friedel and Crafts, Compt. Rend. ci. 1218. 


4 AROMATIC COMPOUNDS, 


Ethylbenzene is a liquid possessing a smell like that of 
toluene; it boils at 136°5° and has a sp. gr. of 0°8664 at 22°5°. 
It is oxidized to benzoic acid by-dilute nitric acid or chromic 
acid, while when a solution of chromium trioxide in glacial 
acetic acid is employed, a little methylphenylketone is always 
formed.1 Ethylbenzene also occurs, together with toluene in 
bone-oil.” 

a-Hihylphenol, C,H,(C,H;)OH, is formed by fusing a-ethy]l- 
benzenesulphonic acid with caustic potash? It smells precisely 
like ordinary phenol, boils at 214°-215° and crystallizes in 
needles or transparent prisms, which melt at 47°-48°, and are 
readily soluble in alcohol, and to some extent in water; the 
solution is coloured a dirty greyish blue by ferric chloride. 
It decomposes into ethylene and phenol when heated with 

phosphorus pentoxide.* 

_ B-Ethylphenol has been prepared from -ethylbenzenesul- 
phonic acid (Beilstem and Kuhlberg) and from crude nitro- 
ethyl benzene, the reduction product of this being treated in 
hydrochloric acid solution with potassium nitrite. It is a 
liquid, which boils at 212°, does not solidify at — 18°, and 
gives a greenish blue colouration with ferric chloride. It is 
converted into salicylic acid by fusion with caustic potash. 

This ethylphenyl, together with other products, is formed, 
according to Auer, when a mixture of absolute alcohol and 
phenol is heated with zine chloride.6 Errera has, however, 
shown that a mixture of ethylphenols is thus obtained, in which 
the a-compound predominates.’ 

The phlorol, which Hlasiwetz obtained by the distillation of 
phloretinic acid, C,H,(OH)CO,H, with lime§ is, according to 
Oliveri, identical with #-ethylphenol. On heating it ae 
methyl iodide, caustic potash, and wood-spirit, he obtained the 
methyl ether, C,H,(C,H;)OCH,, as a strongly refractive liquid 
boiling at 185°.9 A compound of the same formula was found 
by Ciamician among the products of distillation of gum-am- 
moniac with zinc dust; it boils at about 190°-192°, and yields 

1 Friedel and Bahlson, Bull. Soc. Chim. xxxiii. 615. . 

2 Weidel and Ciamician, Ber. Deutsch. Chem. Ges. xiii. 70. 

3 Beilstein and Kuhlberg, Ann. Chem. Pharm. clvi. 211; Fittig and Kiesow, 
ibid. clvi. 251. 

4 Chrustchow, Ber. Deutsch. Chem. Ges. vii. 1166. 

5 Suida and Plohn, Monatsh. Chem. i. 175. 

6 Ber. Deutsch. Chem. Ges. xvii. 619. 

7 Ibid. xviii. Ref. 150. 


8 Ann. Chem. Pharm. cii. 166. 
9 Ber. Deutsch. Chem. Ges. xvi. 1879. 


-ETHYLBENZENE. 5 





a phenol, which, since it boils at 220° and is converted into 
salicylic acid by fusion with caustic potash,! is probably impure 
§-ethylphenol. 

The isobutyric ether of an isomeric phenol, boiling at 224°- 
225° occurs in the ethereal oil from the root of Arnica montana. 
This is probably meta-ethylphenol, since the oil also contains 
methylthymol, C;H,(OCH,)C,H,, which belongs to the meta- 
series. $-Ethylphenol is certainly the ortho-compound, and 
the solid ethylphenol must therefore be the para-compound. 

2275 Chlorethylbenzene, Cs;H,(C,H,)Cl. When ethylene is 
passed into a heated mixture of chlorobenzene and aluminium 
chloride, all the hydrogen atoms of the chlorobenzene are 
gradually replaced by ethyl; the first product consists of a 
mixture of the three chlorethylbenzenes, in which the meta- 
compound predominates, and which is a pleasant smelling lquid, 
boiling at 179°-182°. On oxidation with chromic acid it yields 
meta- and para-chlorobenzoic acids, while orthochlorobenzoic acid 
is also formed by the action of potassium permanganate.® 

Paradichlorethylbenzene, C;H,(C,H;)Cl,, is obtained in a 
similar manner from paradichlorobenzene. It is a liquid which 
has a pleasant odour and boils at 213°5°4 

Bromethylbenzene, C,H,(C,H;)Br, is formed by the action of 
bromine, which contains iodine, on well-cooled ethylbenzene.° 
It is a colourless liquid which has an aromatic odour, boils at 
199°, and is converted by oxidation into parabromobenzoic acid. 

Dibromethylbenzene, C,H.(C,H,)Br,, is prepared by the further 
action of bromine in the presence of iodine, on the preceding 
compound. It isa liquid which mixes in almost every proportion 
with petroleum spirit, boiling at 80°-90° (Friedel and Crafts). 

Pentabromethylbenzene, C,Br,.C,H;, is formed when dibrom- 
ethylbenzene is treated with bromine and aluminium chloride 
or bromide. It crystallizes in monosymmetric prisms, which 
dissolve at 20° in 11 parts of petroleum spirit, melts at 141°5°, 
and can only be distilled under diminished pressure. 

By means of this compound Friedel and Crafts have determined 
the amount of ethylbenzene which is formed by heating toluene 
with aluminium chloride. When the fraction of the product 


1 Ber. Deutsch. Chem. Ges, xii. 1658. 

2 Sigel, Ann. Chem. Pharm. clxx. 354. 

3 Istrati, Ann. Chim. Phys. [6] vi. 395. 

4 Ann. Chim. Phys. [6] vi. 475. 

5 Fittig and Konig, Joc. cit. ; Thorpe, Zeitschr. Chem. 1871, 131; Schramm, 
Ber. Deutsch. Chem. Ges. xviii. 350. 


6 AROMATIC COMPOUNDS. 


which boils at 138° is treated with bromine containing 1 per 
cent. of iodine, the xylenes are converted into tetrabromoxylenes, 
which dissolve in about 200 parts of petroleum spirit, while the 
ethylbenzene yields the dibromo-compound, which, as already 
stated, is extremely soluble in petroleum spirit; this is freed as 
completely as possible from the xylene derivatives and is then con- 
verted into the pentabromo-compound and weighed. They thus 
found that the fraction boiling at 138° contains 10 per cent. of 
ethylbenzene. 

Paranitro-ethylbenzene, C,H,(C,H;)NO,, is formed, together 
with the ortho-compound, when ethylbenzene is dissolved in nitric 
_acid of sp. gr. 14755 it is a yellow liquid which boils at 245°- 
246° and is converted into paranitrobenzoic acid by oxidation. 

Orthonitro-ethylbenzene boils at 227°-228° and is not attacked 
by chromic acid solution.? 

Ethylbenzenesulphonic acid, C,H,(C,H,;)SO,H, is formed in 
two modifications when ethylbenzene is dissolved in slightly 
fuming sulphuric acid. They both form potassium salts which 
crystallize well and can readily be separated, since that of the 
a-acid, which is the chief product, is much less soluble than that 
of the B-acid.? 

Paramidoethylbenzene, C,H,(C,H;)NH,, is obtained by the 
reduction of paranitro-ethylbenzene,? and is also formed when 
ethylaniline hydrochloride is heated to 300°.4 It is a liquid, 
which boils at 213°-214° and forms a difficultly soluble sulphate. 

Orthamido-ethylbenzene boils at 210°-211° (Beilstein and 
Kuhlberg). 


STYROLYL COMPOUNDS. 


2276 Primary Styrolyl alcohol, C,H,.C,H,OH. This compound 
which is also known as phenylethyl alcohol or benzyl carbinol, 
was first prepared by Radziszewski from phenylacetaldehyde, 
C,H,.CH,.CHO, which was dissolved in dilute alcohol and 
treated with sodium amalgam, the solution being kept neutral 
by the addition of sulphuric acid. It is a liquid which only 
possesses a faint odour and boils at 212° 


1 Beilstein and Kuhlberg, Ann. Chem. Pharm. clvi. 206. 
2 Chrustchow, Ber. Deutsch. Chem. Ges. vii. 1165. 

3 Beilstein and Kuhlberg, Ann. Chem. Pharm. clvi. 206. 
4 Hofmann, Ber. Deutsch. Chem. Ges. vii. 526. 

5 Ibid. ix. 372. 


STYROLYL COMPOUNDS. 7 


Primary styrolyl chloride, C,H,;.C,H,Cl, is formed by the 
action of chlorine on boiling ethylbenzene, and is a liquid which 
boils at 200°-204°, the larger portion being thus resolved into 
hydrochloric acid and styrolene, C,H,.C,H,. This decomposition 
renders it probable that the secondary chloride has been simul- 
taneously formed, as is the case with the paraffins. Phenylpro- 
pionitril, C,H,.C,H,.CN, is produced when the chloride is heated 
with potassium cyanide and alcohol. 

Styrolyl acetate, C,H;.C,H,.0.C,H,O, is obtained by heating 
the alcohol to 150° with acetic anhydride. It is a liquid which 
has a pleasant odour and boils at 224°. 

Styrolylamine, C,H;.C,H,.NH,. This base, which is also 
named phenylethylamine, was first prepared by Fileti by the action 
of zine and hydrochloric acid on cherry laurel oil, which chiefly 
consists of phenylhydroxyacetonitril, C,H,.;CH(OH)CN. He also 
prepared it by the same method from amygdalin, the glucoside 
of this nitril,? while Bernthsen* and Spica‘ obtained it from 
phenylacetonitril, which can also be readily converted into the 
amine by the addition of sodium to its alcoholic solution 
(Ladenburg).° 

It is also a product of the dry distillation of phenylalanine,® 
C,H;.C,H;.(NH,)CO,H, and forms a liquid possessing an un- 
pleasant ammoniacal odour. It boils at 193°, dissolves slightly 
in water, more readily in alcohol, has a strongly alkaline reaction 
and is rapidly changed by exposure to the air into the crystalline 
carbonate, which was mistaken by Bernthsen for the free base. 
Its hydrochloride decomposes on heating into ammonium chloride, 
styrolene and distyrolylamine.’ 

Distyrolylamine, (C,H;.C,H,),NH, is formed simultaneously 
with the primary and tertiary bases by the action of zine and 
hydrochloric acid on phenylacetonitril (Spica) : 


C,H,.CH,.CH,.NH, + C,H,.CH,.CN + 41 = 
(C,H,.CH,.CH,),NH + NH,. 


It is a liquid which boils at 335°-337° under a pressure of 603 
mm. and is slightly soluble in water, forming a solution which is 


1 Fittig and Kiesow, Ann. Chem. Pharm. clvi, 245, 

2 Ber. Deutsch. Chem. Ges. xii. 296. 

3 Ann. Chem. Pharm. elxxxiv. 304. 

4 Ber. Deutsch. Chem. Ges. xiii. 204; Gaz. Chim. ital. ix. 555. 
5 Ber. Deutsch. Chem. Ges. xix. 782. 

6 Erlenmeyer and Lipp, Ann. Chem. Pharm. ccxix. 202. 

7 Fileti and Piccini, Ber. Deutsch. Chem. Ges. xii. 1808, 1700. 


267 


8 AROMATIC COMPOUNDS. 





alkaline to litmus. It readily forms salts with acids, but seems 
not to absorb carbon dioxide from the air. 

Tristyrolylamine, (C,H;.C.H,),N, is an oily liquid, almost 
insoluble in water, but forming an alkaline solution in alcohol. 

Parahydroxystyrolylamine, C,H,(OH)C,H,.NH,. This com- 
pound, which has also received the name of ethyloxyphenylamine, 
is formed as a crystalline sublimate when tyrosine, C,H,(OH) 
CH,.CH(NH,)CO,H, is heated to 270°1 It is only slightly 
soluble in water, has a strongly alkaline reaction, and yields 
ammonia and parahydroxybenzoic acid on fusion with potash.” 

2277 Secondary styrolyl alcohol or methylphenylcarbinol, 
C,H,.CH(OH)CH,, was first prepared by Emmerling and Engler, 
who obtained it by the action of sodium amalgam on a solution 
of methylphenylketone in dilute alcohol,? and was then pre- 
pared by Radziszewski from the acetate which is described 
below.* It is a strongly refractive liquid which boils at 202°- 
203° and has a very disagreeable odour. 

Secondary styrolyl ethyl ether, C,A,CH(OC,H,)CH,, was ob- 
tained by Thorpe as a pleasant smelling liquid. by heating the 
bromide with alcoholic ammonia; it boils at 185°-187°.° 

Secondary styrolyl chloride, C,H;.;CHC1.CH,, is formed when 
hydrochloric acid gas is passed into the alcohol,® and, together 
with acetic acid, when the alcohol is treated with acetyl chloride 
(Radziszewski). It is a liquid which boils with decomposition 
at 194°, 

Secondary styrolyl bromide, C,H;.CHBr.CHg, is obtained by 
the action of bromine on boiling ethylbenzene,’ which is there- 
fore attacked by chlorine and bromine in exactly the same 
manner as the paraffins (Part I. p. 135). It may also be prepared 
by the action of hydrobromic acid on the alcohol. It is a 
strongly refractive liquid, which is to a large extent resolved 
into hydrobromic acid and styrolene by distillation at the 
ordinary pressure, but boils at 148°-152° without decomposition 
under a pressure of 500 mm. (Thorpe). 

Secondary styrolylacetate, C,H,.CH(O.CO.CH,)CH,, was pre- 
pared by Radziszewski from the bromide by the action of silver 


1 Schmitt and Nasse, Ann. Chem. Pharm. cxxxiii. 214. 
2 Barth, ibzd. clii. 101. 

3 Ber. Deutsch. Chem. Ges. vi. 1005. 

4 Ibid. vii. 140. 

5 Zeitschr. Chem. 1871, 181. 

6 Engler and Bethge, Ber. Deutsch. Chem. Ges. vii. 1127. 
7 Berthelot, Bull. Soc. Chim. x. 348. 


PHENYLACETYL COMPOUNDS. 9 


acetate and glacial acetic acid. It is a liquid which has a 
pleasant odour, resembling that of jasmine, and boils at 217°- 
220° (Thorpe), at which temperature it is partially resolved into 
styrolene and acetic acid. 

Secondary styrolylamine, C,H,CH(NH,)CHsg, is readily formed 
by the action of sodium amalgam and glacial acetic acid upon 
an alcoholic solution of phenylhydrazine-acetophenone : 


CHy CHy 
C=N—NHC,H,+4H =” SCH.NH, + NH,C,H, 
C,H,“ 


In order to separate the bases, they are converted into the 
sulphates and treated in acid solution with sodium nitrite, until 
a small portion yields no aniline after neutralization with an 
alkali and extraction with ether, the aniline being recognized 
by the bleaching powder reaction. Secondary styrolylamine is 
an oily liquid which has a characteristic odour, boils at 182°- 
185°, and is tolerably soluble in water. The solution has a 
strongly alkaline reaction and deposits the base on the addition 
of concentrated caustic soda solution. It combines with acids 
to form salts which crystallize well, and absorbs carbon dioxide 
from the air, with formation of a crystalline substance which 
melts at 96° and sublimes in stellate groups of needles. The 
phenylhydrazine derivatives of all other ketones and aldehydes 
behave in a similar manner to that of acetophenone, so that 
these oxygen compounds can be readily reduced to amines. 


oH; 


PHENYLACETYL COMPOUNDS. 


2278 Phenylacetaldehyde, C,H;.CH,CHO, was obtained by 
Cannizzaro by heating a mixture of calcium formate and calcium 
phenylacetate” It is also formed when phenyl-lactic acid is 
heated with dilute sulphuric acid to 130° (Erlenmeyer) : 


C,H,.CH,.CH(OH)CO,H = C,H,.CH,.CHO + CH,0,. 


This reaction corresponds exactly with the decomposition of 
ordinary lactic acid into acetaldehyde and formic acid.? It can 


1 Tafel, Ber. Deutsch. Chem. Ges. xix. 1924. 

2 Ann. Chem. Pharm. cxix. 253; exxiy. 252; Radziszewski, Ber. Deutsch. 
Chem. Ges. ix. 372. 

3 Ber. Deutsch. Chem. Ges. xiii. 303. 


10 AROMATIC COMPOUNDS. 


more readily be prepared by boiling phenylbromolactic acid with 
sodium carbonate solution, or by distilling a solution of one 
molecule of phenylchlorolactic acid and two molecules of caustic 
soda with dilute sulphuric acid.1 $-Phenylhydroxyacrylic acid, 
C,H,;C(OH)—CH.CO,H, is an intermediate product of this re- 
action, and the aldehyde is therefore also obtained when the 
sodium salt of this (Erlenmeyer and Lipp) or that of the a-acid, 
C,H,CH—C(OH)CO,H (Plochl), is distilled with dilute sul- 
phuric acid. . Phenylglyceric acid, C,H;.CH(OH)CH(OH)CO,H, 
formed by the combination of the phenylacrylic acid with water, 
is a bye-product of all these reactions. Styrolene alcohol is 
then produced from the phenylacrylic acid by the elimination of 
carbon dioxide and readily changes into phenylacetaldehyde. 

Etard obtained this substance from ethylbenzene, which like 
other aromatic hydrocarbons, combines with chromyl chloride 
to form phenylethidenedichlorochromic acid, which is decom- 
posed by water with formation of the aldehyde :? 


C,H,;.CH,.CH(OCrCl,.OH), + H,O = C,H,.CH,.CHO + 4HCl + 
2CrO,,. 


Phenylacetaldehyde is a liquid, which possesses a characteristic 
penetrating odour and boils at 203°-207°, a portion simultane- 
ously losing water and being converted into a resinous mass. 
It forms a compound with acid sodium sulphite which crys- 
tallizes in small lustrous plates. Nitric acid oxidizes it to 
benzoic acid. 

Paranitrophenylacetaldehyde, C,H,(NO,)CH,.CHO is formed 


by boiling barium #-paranitrophenylchlorolactate with water : 


(C,H,(NO,)CHCI.CH(OH)CO,),Ba = 
2C.H,(NO,)CH,.CHO + 2CO, + BaCl,. 


It crystallizes from hot water in fascicular groups of needles 
melting at 85°—86°.4 

2279 Phenylacetic acid, C,H;.CH,.CO,H. In the year 1856, 
Cannizzaro obtained an acid by heating benzyl chloride with 
potassium cyanide, and boiling the nitril thus formed with caustic 
potash, and considered it to be identical with the substance 
which Noad had previously prepared by the oxidation of 


1 Erlenmeyer and Lipp, Ann. Chem. Pharm. ccxix. 179; Ber. Deutsch. Chem. 
Ges, xill. 308. 

2 Plochl, zbid. xvi, 2815. 

3 Ann. Chim. Phys. [5] xxii. 248. 

4 Lipp, Ber. Deutsch. Chem. Ges, xix, 2647. 


PHENYLACETIC ACID. 11 


cymene? (Part IV. p. 418). Anacid of the same composition was 
isolated by Strecker and Moller from the products obtained by 
boiling vulpinic acid with baryta water. They showed that this 
substance differs from Noad’s acid, but is identical with Can- 
nizzaro’s compound and named it alphatoluylic acid. On account 
of its great similarity to benzoic acid, they assumed that it, and 
not Noad’s toluylic acid, is the true homologue of benzoic acid,? 
while Cannizzaro came to the alternative conclusion. The latter 
chemist prepared the aldehydes of the two isomeric acids and 
found that tolualdehyde changes to toluic acid in the air as 
rapidly as oil of bitter almonds to benzoic acid, and that it is 
converted by alcoholic potash into toluylic acid and the cor- 
responding alcohol. By the oxidation of alphatolualdehyde, on 
the other hand, he obtained an acid containing seven atoms of 
carbon, which appeared to be a mixture of benzoic and _ nitro- 
benzoic acids. Since Strecker and Moller had found that 
alphatoluylic acid is converted into benzaldehyde by oxidation, 
he concluded that Noad’s toluic acid is the true homologue of 
benzoic acid, but that alphatoluic acid was still a member of 
the benzoic series.® 

The isomerism of these acids was shortly afterwards explained 
by Kekulé ina simple manner. He says: “ Toluic acid stands 
in the same relation to toluene as benzoic acid to benzene; it 
therefore contains two side-chains: CH, and CO,H. Alpha- 
toluic acid, on the other hand, contains a lengthened side- 
chain; the group CO,H is connected with the carbon of the 
CH, side-chain : : 


(C,H, CH,)CO,H. (C.H,)CH,,.00,H. 
Toluic Acid, Alphatoluic Acid. 


Toluic acid may therefore be designated methylphenylformic 
acid, and alphatoluic acid as phenylacetic acid. 

The latter acid was then prepared by Crum Brown from 
mandelic acid or phenylhydroxacetic acid, C,H,.CH(OH) CO,H, 
by heating with hydriodic acid and phosphorus.® Kraut 
obtained it by fusing atropaic acid, CH,—C(C,H,)CO,H, with 
caustic potash,® and Zincke prepared it synthetically by heating 
bromobenzene to 180°—200° with ethylchloracetate and copper 


1 Ann Chem. Pharm. xcvi. 246. 2 Ibid. exiii. 64. 
3 Ibid. exxiv. 252. 4 Ibid. exxxvii. 150. 
5 Zeitschr. Chem. 1865, 443. 6 Ann. Chem. Pharm. exlviii. 242. 


12 AROMATIC COMPOUNDS. 


powder.t E. and H. Salkowski found it among the products of 
the pancreatic putrefaction of albumen and wool.? In order 
to prepare it, 60 grms. of pure potassium cyanide are dis- 
solved in 55 grms. of water, contained in a flask connected 
with an inverted condenser, and a mixture of 100 grms. of benzyl 
chloride and 100 grms. of alcohol gradually added to the warm 
solution, which is then boiled for three hours, freed from the 
upper layer and distilled. The portion which passes over below 
236° is carefully added to a solution of 45 grms, of caustic potash 
in 25 grms. of water, and the mixture heated for 5-6 hours, 
until ammonia is no longer evolved, after which the alcohol 
is distilled off, the saline residue dissolved in as small a quantity 
of water as possible, and the phenylacetic acid precipitated in 
the filtered solution with hydrochloric acid. 

The nitril may be more simply decomposed by heating it 
with three times its weight of a mixture of three volumes of 
sulphuric acid and two of water in a flask provided with a wide 
conducting tube, bent twice at right angles, which passes into 
a flask containing water, the end of the tube being situated just 
above the surface of the water. The mixture is heated until 
bubbles of steam commence to be formed, the flame being then 
removed. A violent reaction soon sets in, a portion of the nitril 
passing over into the condenser. After cooling, the pre- 
cipitated phenylacetic acid is filtered off and washed with 
water, the washings being subsequently extracted with ether.‘ 

It can also be readily prepared from benzaldehyde ; to this 
is added rather more than one molecule of pure’ potassium 
cyanide moistened with water, fuming hydrochloric acid being 
then gradually added with constant agitation. Phenylhydroxy- 
acetonitril is thus formed, and is converted by heating to 
130°—140°, with highly concentrated hydrochloric acid into 
phenylchloracetic acid, C,H;.CHCLCO,H, which is reduced 
by the action of zinc dust and ammonia in the cold to 
phenylacetic acid.® 

Properties.—Phenylacetic acid is freely soluble in alcohol and 
ether, but only slightly in cold water, more readily in hot 
water, from which it separates in oily drops until the temper- 


1 Ber. Deutsch. Chem. Ges. ii. 737. 
2 [bid. xii. 648. 

3 Mann, ibid. xiv. 1645. 

4 Stidel, zbid. xix. 1949. 

5 Spiegel, ibid. xiv. 239. 


THE PHENYLACETATES. 13 


ature has fallen below the melting point of the acid, after which 
it crystallizes in thin, iridescent, poimted plates, which resemble 
those of benzoic acid and belong to the rhombic system. It 
melts at 76°5°, sublimes below 100° and boils at 265°5°, forming 
an irritating vapour which produces coughing. On hon 
with manganese dioxide and dilute sulphuric acid it yields 
formic acid, benzaldehyde and benzoic acid. 

2280 The phenylacetates. The salts of the metals of the 
alkalis and alkaline earths are very readily soluble. 

Calcium phenylacetate, (C,H;.CH,.CO,.),Ca + 3H,O, crystal- 
lizes in needles, 

Silver phenylacetate, C,H,.CH,.CO,Ag, is a precipitate con- 
sisting of fine plates, which can be recrystallized from hot water. 
The copper salt is an amorphous green precipitate. 

Methyl phenylacetate, C,H;.CH,.CO,.CH,, is obtained by the 
action of hydrochloric acid on a solution of the acid in methyl 
alcohol, and is a liquid which possesses a faint but agreeable 
odour and boils at 220°. | 

Lihyl phenylacetate, C,H;.CH,.CO,.C,H,, is prepared in a 
similar manner? and also by the action of ethyl iodide on the 
potassium salt.? It boils at 226° and hasa very pleasant odour. It 
is also formed when hydrochloric acid gas is passed into a heated 
alcoholic solution of phenylacetonitril.* 


Boiling-point. 


Propyl phenylacetate, C,H,.CH,.CO,C,H, .. . 238° 
Isobutyl phenylacetate, G, H, CH, CO, CH, CH(CH)) 24:7° 
Benzyl! phenylacetate,* C,H, ‘CH, ‘CO CH,. Gigs SavS1ae 


Phenylacetyl chloride,C,H;.CH,.COCI,was obtained by Strecker 
and Moller from the acid by the action of phosphorus penta- 
chloride, while Popow prepared it from the calcium salt and 
phosphorus oxychloride.® It is a colourless, fuming liquid, 
which decomposes very readily, especially on distillation,® and 
has therefore not yet been prepared pure. 

Phenylacetamide, C,H;.CH,.CO.NH,, is formed by the action 
of ammonia on the chloride (Strecker and Moller). It is also 
obtained when the ethyl ether is heated with ammonia to 


1 Radziszewski, Ber. Deutsch. Chem. Ges. ii. 207. 

2 Hodgkinson, Journ. Chem. Soc. 1880, i. 480. 

3 Hauff, Ber. Deutsch. Chem. Giles. xx. 592. 

4 Journ. Chem. Soc. 1880, i. 480; Slawik, Ber. Deutsch. Chem. Ges. vii. 1051. 
5 Ibid. v. 550. 

6 Hofmann, ibid. xiii. 1234. 


14 AROMATIC COMPOUNDS. 





140°-150°! and by heating the nitril with an alcoholic solution of 
potassium hydrosulphide.? It crystallizes in small plates which 
have a satin-lustre, or thin tablets which are slightly soluble in 
cold, readily in hot water and alcohol, and melt at 154°—155°. 

Phenylaceturic acid, C,H,;.CH,.CO.NH.CH,.CO,H, was de- 
tected by E. and H. Salkowski in the urine of dogs, to which 
15-2 grms. of phenylacetic acid, generally combined with soda, 
were administered daily with their food. E. Salkowski then 
discovered that it is a normal constituent of the urine of the 
horse,t and Hotter obtained it by the action of phenylacetyl 
chloride on an alkaline solution of amidoacetic acid. It 
crystallizes from hot water in aggregates of thin plates, or in 
compact pointed prisms, melting at 143°. On boiling with 
hydrochloric acid, it decomposes into phenylacetic acid and 
amidoacetic acid. 

2281 Phenylacetonitril, C,H;.CH,.CN, was first prepared, as 
already mentioned, by Cannizzaro, who named it benzyl cyanide, 
by heating an alcoholic solution of benzyl chloride with potassium 
cyanide. He did not however investigate its properties more 
fully, but converted it into phenylacetic acid; Radziszewski 
subsequently prepared it pure by the same reaction.® Triben- 
zylamine * and phenylacetamide*® have been noticed as bye- 
products in its preparation. Barbaglia then showed that it is 
also formed by the distillation of potassium benzylsulphonate 
with potassium cyanide. The occurrence of this nitrilin nature 
is especially interesting ; Hofmann found that it forms the chief 
constituent of the ethereal oils of the garden nasturtium 
(Tropaeolum majus) and common cress (Lepidiwm sativwm).)° 

It is prepared by Mann’s method, which is described under 
phenylacetic acid, the product being freed from alcohol, distilled 
with steam, dried and rectified. It is a colourless liquid which 
has a faint but characteristic odour and boils at 232°. 

Phenylbromacetimido-bromide, C,H,Br,N, is formed, together 


1 Ber. Deutsch. Chem. Ges. vili. 692 ; Bernthsen, Ann. Chem. Pharm. clxxxiv. 
294, 316. 

2 Weddige, Journ. Prakt. Chem. [2] vii. 99. 

3 Ber. Deutsch. Chem. Ges. xii. 6538. 

4 Ibid. xvii, 3010. 

5 Ibid. xx. 81. 

6 Ber, Deutsch. Chem. Ges. iii. 198. 

7 Frankland and Tompkins, Jowrn. Chem. Soc. 1880, i. 566. 

8 Ber. Deutsch. Chem. Ges. xiii. 741. 

9 Ibid, v. 270. 

10 Tbid. vii. 518 and 1298. 


PHENYLACETONITRIL. 15 


with phenylbromacetonitril, by heating phenylacetonitril with 
bromine. The oily product, which has a very disagreeable odour, 
a pungent taste, and a vapour which violently attacks the eyes, 
deposits crystals of the compound on standing, more rapidly on 
the addition of a large quantity of ether. It is formed accord- 
ing to the following equation : 


C.H,.CH,.CN + Br, = C,H,CHBr.CN + HBr = 


CH, CHBr.0€ 
Br, 

It is only very slightly soluble in all solvents, most readily in 
boiling glacial acetic acid. On heating to 150° with dilute hydro- 
chloric acid it is converted into phenylhydroxyacetic acid, 
C,H;.CH(OH)CO,H.! 

Cyanbenzine, C,,H,,N,, is formed in small quantity, together 
with other products, by the action of zinc ethyl on phenylaceto- 
nitril, and crystallizes from hot alcohol in fascicular aggregates 
of needles, which melt at 170°—171°. 

Benzacin, C,,H,,N,O, is a product of the same reaction as the 
preceding compound; it is more readily soluble in alcohol 


and crystallizes in rhombohedral or hexagonal tablets, melting 
at 150° (Frankland and Tompkins). 


HALOGEN SUBSTITUTION PRODUCTS OF 
PHENYLACETIC ACID. 


2282 These derivatives may be divided into two groups, since 
the substitution may be effected either in the nucleus or in the 
side-chain. In the first case, para-compounds form the chief 
product, ortho-compounds being also formed, while benzoic acid 
yields meta-substitution products. 

Parachlorophenylacetic acid, C,H,CLCH,CO,H. The oily 
nitril of this acid is obtained by heating parachlorobenzyl 
chloride or bromide with alcohol and potassium cyanide,? and 
the free acid is formed when phenylacetic acid is treated with 
chlorine in the sunlight.? It crystallizes from hot water in fine 
needles, which melt at 104° (Jackson and Field), 

1 Reimer, Ber. Deutsch. Chem. Ges. xiv. 1797. 
2 Neuhof, Ann. Chem. Pharm. cxlvii. 347 ; Jackson and Field, Ber. Deutsch. 


Chem. Gres. xi. 905. 
3 Radziszewski, bid. ii. 207. 


16 AROMATIC COMPOUNDS. 


Parabromophenylacetic acid, C,H,Br.CH,.CO,H, is formed, 
together with the ortho-acid, by the bromination of phenylacetic 
acid,’ and by heating the corresponding nitril to 100° with hy- 
drochloric acid. It is most conveniently prepared by adding 
bromine in small quantities to a well cooled mixture of phenyl- 
acetic acid, mercuric oxide, and water. The mercury is then 
removed with caustic soda, the brominated acids precipitated in | 
the filtrate with hydrochloric acid and separated by means of 
their barium salts, that of the para-acid being the less soluble.® 
Parabromophenylacetic acid crystallizes from hot water in long, 
flat needles, resembling those of benzoic acid, which melt at 
114°-115°. 

Parabromophenylacetontril, C,H,Br.CH,.CN, is obtained from 
parabromobenzylbromide and potassium cyanide, and crystallizes 
in truncated quadratic pyramids, resembling those of potassium 
ferrocyanide, or forms twin crystals, which have a similar 
appearance to the conventional architectural form of the four- 
leaved clover. It melts at 46° and has a strong, unpleasant 
odour. 

Orthobromophenylacetic acid crystallizes from hot water in flat, 
lustrous needles, and from glacial acetic acid on gradual evapora- 
tion in well-developed monosymmetric prisms, melting at 
103°-104°. Its nitril is an oily liquid, which does not solidify in 
a freezing mixture. 

Para-iodophenylbenzore acid, C,H,1.CH,.CO,H. The nitril of 
this acid, which is prepared from para-iodobenzyl bromide, crys- 
tallizes in nacreous tablets, which have a characteristic odour 
and melt at 50°5°. On heating with hydrochloric acid to 100°, 
it yields the acid, which crystallizes from hot water in poimted 
tablets, which melt at 135° and possess a pleasant odour.° 


NITROPHENYLACETIC ACIDS. 


2283 Radziszewski found that the products of nitration of 
phenylacetic acid consist chiefly of the para-compound, together 
with a smaller quantity of the orthonitro-acid.6 He did not, 


1 Radziszewski, Joc. cit. 

2 Jackson and Lowery, Ber. Deutsch. Chem. Ges. x. 1209. 
3 Bedson, Jowrn. Chem. Soc. 1880, i. 94. 

4 Jackson and White, Ber. Deutsch. Chem. Ges. xiii. 1219. 
5 Jackson and Mabery, Ber. Deutsch. Chem. Ges. xi. 55. 

6 [bid, ii. 209 ; iii. 648. 


NITROPHENYLACETIC ACIDS. 17 


however, obtain the pure compounds, since, according to Max- 
well, these crystallize together and form mixtures with a con- 
stant melting point, in the same way as the nitrobenzoic acids. 
The latter chemist succeeded in preparing the methyl ether of 
the para-compound in the pure state, and from it the acid 
Radziszewski also found that the barium salt of the para-acid 
is less soluble than that of the ortho-derivative. A complete 
separation cannot be effected in this way, but the acids precipi- 
tated from the resulting purified’ salts can be obtained pure by 
recrystallization : * 

Paranitrophenylacetic acid, C,H,(NO,)CH,.CO,H. In order 
to prepare this substance, 2 parts of phenylacetic acid are dis- 
solved in 20 parts of fuming nitric acid, the solution poured into 
4 volumes of water and. allowed to evaporate slowly on the 
water-bath. An impure paranitrophenylacetic acid, melting at 
114°, crystallizes out on cooling; this is dissolved in 3 yoludes 
of aothyl alcohol and the sahenibn saturated with hydrochloric 
acid gas. After a few hours the liquid is heated to drive off 
the excess of methyl alcohol and hydrochloric acid, agitated 
with sodium carbonate solution, and extracted with ether; the 
methyl paranitrophenylacetate crystallizes from the oily deadiiis 
left on the evaporation of the ethereal solution, and is purified 
by recrystallization from petroleum spirit. The pure compound 
is neutralized with caustic soda, and the free acid precipitated 
with hydrochloric acid (Maxwell). Bedson obtained the pure 
acid by repeatedly recrystallizmg the acid prepared from the 
slightly soluble barium salt from hot, dilute alcohol. According 
to Gabriel, it is best obtained by heating its nitril to 100° for 
several hours with an excess of hydrochloric acid.’ It crystallizes 
from hot water in long, yellowish, brittle needles, melting at 151°- 
152°. Chromic acid solution oxidizes it to paranitrobenzoic acid. 

Barium paranitrophenylacetate, (C,H,(NO,)CH,.CO,),Ba + 
7H,0, crystallizes from a slowly cooled solution in transparent, 
light yellow, six-sided tablets, which become opaque and effloresce 
in the air. 

Methyl paranitrophenylacetate, Cs§H,(NO,)CH,.CO,.CH,, erys- 
tallizes from alcohol in yellowish tablets, and from petroleum- 
spirit in lustrous needles, two or three inches in length, which 
melt at 54°. 


1 Jackson and Mabery, Ber. Deutsch. Chem. Ges. xii. 1764. 
2 Bedson, Journ. Chem. Soc. 1880, i. xe. 
3 Ber. Deutsch. Chem. Ges. xiv. 2341. 


18 AROMATIC COMPOUNDS. 





Ethyl paranitrophenylacetate, C,H,(NO,)CH,.CO,.C,H;, was 
obtained by Maxwell in a similar manner to the methyl ether, 
while Radziszewski prepared it by the nitration of ethyl phenyl- 
acetate. It crystallizes from petroleum-spirit in broad, thin 
tablets, melting at 65°5°-66°. 

These ethers are coloured a fine violet by caustic potash in 
alcoholic solution. 

Paranitrophenylacetonitrul, C,H,(NO,)CH,.CN, is obtained 
when one part of phenylacetonitril is brought into nine parts of 
fuming nitric acid and the solution precipitated with water ; it 
crystallizes from boiling alcohol in colourless, compact needles, 
melting at 116° (Gabriel). Small quantities of the ortho- and 
meta-compounds are simultaneously formed (Salkowsk1). 

Orthonitrophenylacetic acid. When the mixture of nitro-acids 
is crystallized from alcohol and the mother liquors concen- 
trated, or when the more readily soluble barium salt is decom- 
posed with hydrochloric acid, an acid is obtained which crystallizes 
in fascicular needles and melts at 112°-117°. If this be dis- 
solved in wood-spirit or ordinary alcohol and the solution allowed 
to evaporate spontaneously, the ortho-compound is deposited in 
large crystals, which are then purified by recrystallization. It 
forms needles or monosymmetric tablets, which melt at 141° 
(Salkowski), and are oxidized to orthonitrobenzoic acid by 
potassium permanganate. 

Barium orthonitrophenylacetate, (C,H,(NO,)CH,CO,),Ba + 
2H,O, crystallizes in white, lustrous scales. 

Orthonitrophenylacetonitril separates from solution in glacial 
acetic acid in large, well-formed rhombic prisms, which melt at 
84° and are readily converted into the acid by heating with 
hydrochloric acid (Salkowski). The nitril may also be obtained 
by heating an alcoholic solution of orthonitrobenzyl chloride 
with potassium cyanide. A larger quantity of dinitrocyandt- 
benzyl, C,H,(NO,)CH(CN)CH,.C,H,NO,, is always simultane- 
ously formed; this substance may also be prepared by heating 
orthonitrobenzyl chloride with orthnitrophenylacetonitril, and 
crystallizes in short, thick prisms, which melt at 110°5°1 

Metanitrophenylacetic acid was prepared by Gabriel and Borg- 
mann from its nitril;? it crystallizes from hot water in long 
thin needles, melting at 120° (Salkowski). 


1 Bamberger, Ber Deutsch. Chem. Ges. xix. 2635. 
2 Ibid. xvi. 2064 ; Borgmann, Chem. Centralbl. 1855, 456. 


AMIDOPHENYLACETIC ACIDS. 19 


Metanitrophenylacetonitril forms large, well-developed mono- 
symmetric crystals, melting at 61° 

Dinitrophenylacetie acid, C,xH,(NO,),CH,.CO,H (4:2:1), was 
obtained by Radziszewski by the action of a mixture of 
sulphuric and nitric acids on paranitrophenylacetic acid. In 
order to prepare it, 50 grms. of phenylacetic acid are added in 
small quantities to 300 grms. of red fuming nitric acid, 500 grms. 
of sulphuric acid being then added and the mixture poured into 
ten volumes of cold water after standing for ten minutes? It 
crystallizes from hot water in fine yellowish needles, which melt 
at 160° and decompose at a higher temperature into carbon 
dioxide and ordinary dinitrotoluene. The alkali salts of the 
acid undergo this decomposition in aqueous solution at the 
ordinary temperature and instantaneously on boiling : 


C,H,(NO,),CH,.CO,K +H,0 = C,H,(NO,),CH, +CO,KH. 


Bergmann obtained two nitro-acids by the further nitration 
of metanitrophenylacetic acid, one of which is soluble in 
benzene and melts at 137°, while the other is insoluble and 
melts at 152°. 


AMIDOPHENYLACETIC ACIDS. 


2284 Paramidophenylacetic acid, C,H,(NH,)CH,.CO,H, is 
obtained by the reduction of paranitrophenylacetic acid with 
tin and hydrochloric acid. It crystallizes from hot water in 
white iridescent plates, which become coloured brown in the air 
and melt with decomposition at 199°—200°, (Bedson). 

Paramidophenylacetonitril, C,H,0NH,)CH,.CN, has been 
prepared by the reduction of paranitrophenylacetonitril; it 
crystallizes from hot water in broad plates, which melt at 
43°5° — 44°5°.3 

Orthonitroparamidophenylacetic acid, C,H,(NH,)(NO,)CH,,. 
CO,H, (4:2:1) is formed by the reduction of the dinitro-acid 
by means of aqueous ammonium sulphide and crystallizes from 
hot water in long, broad, yellowish red to reddish brown needles, 


1 Salkowski, Ber. Deutsch. Chem. Ges. xvii. 504. 
2 Meyer and Gabriel, ibid. xiv., 823. 
3 Czumpelik, bid. iii, 474 ; Gabriel, ibid. xv. 835. 


20 AROMATIC COMPOUNDS. 


which melt at 184°—186°. The following reaction takes place 
when it is subjected to the action of amyl nitrite and an excess 
of hydrochloric acid : 


NH,,.C,H,(NO,)CH,.CO,H + 2NO,H + HCl= 
CIN—NC,H,(NO,)C—N.OH + CO, +3H,0. 


The diazo-compound obtained in this way forms long, lustrous, 
pale red needles, and decomposes on heating with alcohol with 
formation of orthonitrobenzaldoxime (Part IV. page 146). The 
ethyl ether, which is prepared by the action of hydrochloric acid 
on the alcoholic solution of the acid, crystallizes in long, fine, 
yellow needles, which melt at 100°. When it is brought into a 
heated mixture of concentrated hydrochloric acid and ethyl 
nitrate, ethyl isonitrosonitrophenylacetate is formed ; this substance 
crystallizes from hot water in long yellowish needles, which melt 
at 163° and decompose on heating with formation of orthonitro- 
benzoic acid.? 


C,H,(NO,)C(NOH)CO,.C,H, + 2HCl+H,0 = 
C,H,(NO,)CO,H + C,H,Cl + CO, + NH,Cl. 


The same compound is formed by the action of hydroxylamine 
on ethyl orthonitrobenzoyl formate,? C,H,(NO,)CO.CO,.C,H,. 

Metanitroparamidophenylacetic acid, C,H,(NH,)(NO,).CH,. 
CO,H (4:3:1), is prepared by heating paramidophenylacetonitril 
with acetic anhydride and treating the product with concentrated 
nitric acid, the acetyl-derivative metanitroacetamidophenylaceto- 
nitru, C,H.(NO,)NH(C,H,0)CH,CN, being thus formed. It 
crystallizes in sulphur-yellow, flat needles or plates, which melt 
at 112°—113° and yield the nitro-amido-acid on boiling with 
concentrated hydrochloric acid. This substance crystallizes from 
hot water in broad orange-yellow tablets or pointed needles and 
melts at 143°5°—1445°, It also yields a diazo-compound which 
crystallizes in light red, rectangular tablets or pointed needles 
and is converted into metanitrobenzaldoxime by heating with 
alcohol.? 

Metamidophenylacetie acid, C,H,(N H,)CH,.CO,H, crystallizes 
from hot water in small, yellowish tablets, which melt at 148°— 
149° (Gabriel and Borgmann). 


1 Gabriel and Meyer, Ber. Deutsch. Chem. Ges. xiv. 823: Meyer. Chem. 
Centralbl. 1855, 516. 

2 Gabriel, Ber. Deutsch. Chem. Ges. xvi. 571. 

3 Ibid. xv. 843. 


OXINDOL. 21 


Metamidophenylacetonitril, C,H,(NH,)CH,.CN, is an oily 
liquid, which does not solidify at —17° (Salkowski). 

Ortho-amidophenylacetic acid is not known to exist in the free 
state, since, like other ortho-compounds, it immediately loses 
water and passes into the anhydride : 


ari Pave Oe. ee TaaNae hate 
Qn 6 ‘ne ¥ aes 

Oxindol, as this substance has been named, was first prepared 
by Baeyer and Knop? by the reduction of csatin C,H,NO,, an 
oxidation product of indigo, which will be subsequently 
described. Baeyer,? and also Bedson? then succeeded in 
obtaining it by the reduction of orthonitrophenylacetic acid. 

In order to prepare it from isatin, this is suspended in water 
to which 5 per cent. sodium amalgam is gradually added, the 
temperature not being allowed to rise. The liquid first becomes 
coloured dark violet, then brown and finally a dirty yellow, 
dioxindol, C,H,NO,, which cannot be further reduced in alkaline 
solution, being formed. The solution is then diluted with water 
until 100 parts of this are present for every part of isatin em- 
ployed, this degree of dilution being necessary to prevent the 
formation of condensation products. It is then acidified with hy- 
drochloric or sulphuric acid, heated in bath of boiling water and 
again treated with sodium amalgam, the liquid being kept acid 
throughout the operation. When the solution retains its ight 
yellow colour even when rendered alkaline, it is neutralized with 
sodium carbonate and evaporated until oily drops are formed 
on the surface. The oxindol separates on cooling in long, 
yellow, strongly refractive needles, an additional quantity of 
which can be obtained by concentration. 

It may be more easily prepared from orthonitrophenylacetic 
acid, which need not be pure. This is reduced in the cold with 
tin and hydrochloric acid, the tin precipitated with sulphuretted 
hydrogen and the filtrate boiled with calcium carbonate. The 
oxindol is then removed from the solution by ether, while calcium 
paramidophenylacetate remains behind, After repeated crystal- 
lization from hot water the oxindol forms long, colourless needles 
or feathery groups; it melts at 120°, and distils without decom- 
position when a small quantity is heated. 


1 Ann. Chem. Pharm. eet 2 Ber. Deutsch. Chem. Ges. xi. 583. 
3 Jowrn. Chem. Soc. 1880, i. 93. 


22 AROMATIC COMPOUNDS. 


Oxindol silver, C;H,AgNO, is obtained by the careful addition 
of ammonia to a solution of oxindol and silver nitrate, in the 
form of a flocculent precipitate which becomes granular on 
standing. 

Oxindol hydrochloride, C,H,NO.HCI, forms pointed crystals 
which are readily soluble in water. 

Ethyloxindol, C,H,(C,H,)NO, is formed by heating an alcoholic 
solution of oxindol with sodium ethylate and ethyl iodide. It 
is an oily, faintly smelling liquid, which is not decomposed when 
heated with baryta water or hydrochloric acid. 

Acetoxindol, C,H,(C,H,0)NO, is obtained by boiling oxindol 
with acetic anhydride, and crystallizes from hot water in long 
needles, melting at 126°. When it is dissolved in cold caustic 
soda, and the solution acidified with sulphuric acid, acetortho- 
amidophenylacetic acid is precipitated : 


i, 08, C0.0H 
HX >00 + H,O = OFC 
N.CO.CH, NH(CO.CH,). 


This body, which has not yet been obtained perfectly pure, 
forms a crystalline mass, which is again converted into oxindol by 
heating with caustic soda or hydrochloric acid.” 

Nitro-oxindol, C,H,(NO,)NO, was prepared by Baeyer by the 
addition of saltpetre to a solution of oxindol in sulphuric acid. 
It crystallizes from hot water in yellow needles or granules, 
which decompose at 175°. 

Paramido-oxindol, C,H,(NH,)NO, is formed by the action of 
tin and hydrochloric acid on dinitrophenylacetic acid : 


NO 
C.HA(NO) + 19H = C,H,(NH. KE 0 
CH,,CO.0OH 
5H,0. 


It crystallizes from hot water in long needles, which have a 
vitreous lustre and become dark-coloured in the air. It combines 
with acids to form salts, which crystallize well.* 

A compound isomeric with this has been prepared from 
oxindol, which is converted by nitrous acid into a compound 


1 Baeyer and Comstock, Ber. Deutsch. Chem. Ges. xvi. 1704. 
2 Suida, Ber. Deutsch. Chem. Ges, xii. 1236. 

3 Ibid. xii. 1313. 

4 Gabriel and Meyer, zbid. xiv. 832. 


HYDROXYPHENYLACETIC ACIDS. 23 
* 
which was formerly thought to be nitroso-oxindol, but was sub- 
sequently recognised as isatinoxime, and is converted by reduction 
into the isomeric amido-oxindol, which will therefore be descr ibed 
under isatin. 
Chloroxindol chloride, C,H,C1,N, is the product of the action 
of phosphorus pentachloride on oxindol : 


on roe 
HK ee + 2PCl, = C, HS ii Jul + POC), 
PCI, + 2HCL. 
It crystallizes from hot water in lustrous plates, which are readily 
soluble in alcohol and ether, and melt at 103°—104° It has a 
characteristic pungent, feecal odour, and is volatile with steam. 
It dissolves in caustic potash without change, and is not attacked 
by sodium amalgam either in acid or alkaline solution, while it 
is converted into indol, C,H,N, on heating with zinc dust. 
Retindol is formed when the chloride is brought into glacial 
acetic acid saturated with hydriodic acid. It is precipitated by 
water in white amorphous flocks, and is converted into indol by 
dry distillation, a portion being, however, carbonized.' 


HYDROXYPHENYLACETIC ACIDS, 
C,H,(OH)CH,.CO,H. 


2285 Parahydroxyphenylacetic acid was discovered by E. and 
H. Salkowski in the products of the putrefaction of wool,? and 
was afterwards detected by Baumann in human urine,? and by 
Brieger in a putrid, pleuritic exsudation H. Salkowski then 
prepared it by the action of nitrous acid on paramidophenyl- 
acetic acid,> and, in conjunction with his brother, detected it 
among the putrefaction products of albumen.’ It may also be 
obtained by the action of hydrochloric acid or caustic soda on 
its nitril. 

1 Baeyer, Ber. Deutsch. Chem. Ges, xii. 457. 
2 Ber. Deutsch. Chem, Ges. xii. 648. 

3 Ibid. xiii. 279. 

4 Zeitschr. phyzikal. Chem. v. 367. 


5 Ber. Deutsch. Chem. Ges. xii. 1438. 
6 Ibid. xiii. 189. 


268 


~ 


24 AROMATIC COMPOUNDS. 
ag 


It is tolerably soluble in cold, readily in hot water, and crys- 
tallizes in very brittle prismatic needles, which melt at 148°, and 
sublime to a small extent without decomposition, a portion of 
the residue being always decomposed. Its aqueous solution is 
coloured greyish-violet by ferric chloride, but this soon passes 
into a dirty greyish-green. On distillation with lime it yields 
paracresol. 

Parahydroxyphenylacetonitril, C,H,(OH)CH,.CN, was first ob- 
tained from sinalbin (Part IV. page 377), by Laubenheimer and 
Will, and was then prepared by H. Salkowski by the action of 
nitrous acid on paramidophenylacetonitril! It crystallizes in 
large, lustrous, monosymmetric tablets, which melt at 69°—70°, 
are slightly soluble in cold, readily in hot water, and give a 
violet colouration with ferric chloride. 

Methylparahydroayphenylacetic acid, C,H,OCH,)CH,.CO,H, 
was first prepared by Cannizzaro, who heated anisyl chloride 
(Part IV. page 332) with potassium cyanide and alcohol, and then 
decomposed the nitril thus obtained with caustic potash. It crys- 
tallizes from hot water in nacreous plates melting at 85°—86° 

Methylparahydroxyphenylacetonitrul, C,H,(OCH,)CH,.CN, is 
also formed when parahydroxyphenylacetonitril is heated with 
‘caustic potash and methyl iodide. It is a liquid which readily 
yields the acid on heating with hydrochloric acid (Salkowsk1). 

Metahydroxyphenylacetic acid has been prepared from its nitril 
and from metamidophenylacetic acid. It is so soluble in water 
that it can only be removed from solution by evaporation to 
dryness. It crystallizes from a hot mixture of petroleum spirit 
and benzene in fine needles, more compact crystals being formed 
when the solution is more gradually cooled. It melts at 129°, 
and yields a fugitive violet colouration with ferric chloride. 

Metahydroxyphenylacetonitril is readily soluble in hot water, 
from which it separates as an oily liquid, which solidifies on 
standing in contact with the solid compound. The latter is 
obtained in rhombic tablets, melting at 52°—58°, by the gradual 
evaporation of the solution. Ferric chloride gives a beautiful 
violet colouration.® 

Orthohydroxyphenylacetic acid has been prepared by Baeyer 
and Fritsch by the reduction of orthohydroxymandelic acid, 
‘C,H,(OH)CH(OH)CO,H, with hydriodic acid. It crystallizes in 

1 Ber. Deutsch. Chem. Ges. xvii. 504. 


2 Ann. Chem. Pharm. exvii. 246. 
3H. Salkowski, Ber. Deutsch. Chem. Ges. xvii. 506. 


DIHYDROXYPHENYLACETIC ACIDS. 25 


needles, which melt at 187°, are tolerably soluble in water, and 
give the same colouration as salicylic acid, with ferric chloride, 

On distillation it is resolved into water and its lactone, which 
corresponds to oxindol : 


OH 04 
OH Oh Hien DCO 4-7FLO. 
**\CH,.CO.0H Fhe He 


It is readily soluble in hot water, crystallizes from ether in 
large rhomboid tablets, melts at 490°, and boils at 236°—238°. It 
is gradually converted into the acid by water, rapidly by alkalis.! 


DIHYDROXYPHENYLACETIC ACIDS, 
C,H,(OH),CH,.CO,H. 


2286 Alphahomoprotocatechwie acid (CH,:0OH:OH=1: 3:4). 
—When aceteugenol is treated in acetic acid solution with 
potassium permanganate, acetylalphahomovanillic acid is formed, 
together with acetylvanillin and acetylvanillic acid : 


//CH,.CH=0H, /CH,.0O,H 
C,H,WOCH, + 50=C,H,COCH, +H,0+CO,. 
\O.CO. CH, *\O.CO0.CH 


3 


On heating with caustic soda it is converted into alphahomo- 
vanillic acid, which yields methyl chloride and alphahomoproto- 
eatechuic acid on heating with hydrochloric acid to 170°—180°. 
This is extremely soluble in water and alcohol, but almost 
insoluble in cold, and only slightly in hot benzene, from which 
it crystallizes in fine, lustrous, transparent needles, melting at 
127°. Ferric chloride produces a grass-green colouration in the 
aqueous solution ; this colour changes through dark green and 
blue to a reddish violet on the gradual addition of sodium 
carbonate solution or ammonia. It is a strong acid, and forms 
well-defined salts; like protocatechuic acid, it reduces Fehling’s 
solution and ammoniacal silver nitrate solution. On fusion with 
potash it yields protocatechuic acid. 

Alphahomovanillic acid, C,H,(OCH,)(OH)CH,.CO,H, is slightly 


1 H. Salkowski, Ber. Deutsch. Chem. Ges. xvii. 978. 


26 AROMATIC COMPOUNDS. 





soluble in cold, readily mm hot water and alcohol, and _ crystal- 
lizes in transparent, six-sided prisms, which melt at 142°—143° 
Alphahomoveratric acid, C,H,(0CH;),CH,.CO,H, is formed 
when the preceding compound is heated with caustic potash and 
ethyl iodide, and crystallizes from water in fine white needles, 
containing water of crystallization which is gradually lost over 
sulphuric acid. The anhydrous acid melts at 98°—99°.? 
Paracoumarhydrin, C,H,0,. This substance, which is meta- 
meric with coumaric acid, C,H,(OH)C,H,.CO,H, is formed 
when paracotein, C,,H,,0,, 1s heated with caustic potash, and 
crystallizes in plates, which smell like coumarin, and melt at 
82°—83°, An acid, which probably has the formula C,H,O,, is 
also formed in the reaction; 1¢ is very similar to the piperonylic 
acid which occurs with paracotein in the Paracoto-bark (Part IV. 
p. 855). Paracoumarhydrin appears therefore to be homologous 
with piperonal, and, since paracoteIn yields protocatechuic acid 
on fusion with potash, has probably the following constitution : 
O 
c.H,Z0> CEs 
\CH,,.CHO. 


STYROELNE, ETHENYLBENZENE, OR 
PHENYLETHYLENE, O,H,.CH—CH,, 


2287 Bonastre, by the distillation of liquid styrax* with 
water, obtained a volatile oil, which was more closely investigated 
by Simon, who decided that it was a hydrocarbon isomeric with 


1 Tiemann and Nagai, Ber. Deutsch. Chem. Ges, x. 201. 

2 Tiemann and Matsmoto, zbid. xi. 143 ; Nagai, ibid. xi. 658. 

3 Jobst and Hesse, Ann. Chem. Pharm. cxcix. 30. 

* Liquid styrax (styrax liquidus) is mentioned at a very early date by the 
Grecian and Arabian physicians, and was exported by the Arabs to India and 
China, which still receive the larger portion of the annual production. Its origin 
was very doubtful, and it has only recently been ascertained with certainty that it is 
derived from Liquidambar orientalis, a tree which forms forests in the south-west 
of Asia Minor. In order to obtain the balsam the exterior bark is removed, and 
the interior cut off with a specially constructed knife, and boiled in copper vessels 
with sea water. The resinous sap is thus separated, and can be skimmed off the 
liquid, a further quantity being obtainable by pressing the boiled bark (Fliickiger 
and Hanbury, Pharmacographia, 2nd ed. p. 271). 

Liquid styrax contains styrolene, cinnamic acid, cinnamyl cinnamate, 
C.Hs.C.H,.CO,.C3H,.CgH;, phenylpropyl cinnamate, C,H,.C,H,.CO,.C,;H,.C,H;, 
some ethyl cinnamate, and a small quantity of a pleasant-smelling substance, 
which is probably ethylvanillin. The chief constituent, however, is the resinous 
storesin, C3,H5;(0H)s, and its cinnamic ether (Miller, Ann. Chem. Pharm. 
elxxxvili. 184 } clxxxix. 338). 


STYROLENE. 27 


benzene, and named it styrol. By the distillation of cinnamic 
acid with slacked lime, he obtained another hydrocarbon, also 
isomeric with benzene, but different from styrol, and gave it the 
name of cinnamomin.! This substance was prepared in a 
similar manner by Herzog, and named cinnamol.? Mitscherlich, 
however, showed that the body obtained in this way is not a 
single compound, but a mixture of hydrocarbons, among which 
benzene is present.® Gerhardt and Cahours, on the other 
hand, found that when cinnamic acid is distilled with four times 
its weight of baryta, a hydrocarbon with constant boiling-point 
is formed. They determined the composition and vapour.density 
of this substance, and named it cinnamene (cinnaméne).t Accord- 
ing to E. Kopp, this body is identical with styrol, since it 
behaves chemically in a similar manner, and does not differ from 
it more than the different kinds of turpentine from one another. 
Blyth and Hofmann confirmed the results of Mitscherlich and 
Gerhardt and Cahours, and showed in addition that, as Simon 
had previously observed, styrol is converted on heating into a 
solid body, which, however, preserves its original composition, and 
was therefore named metastyrol. They prepared a number of 
derivatives of styrol, all of which pointed to C,H, as its formula ; 
they observed, however, that when it and cinnamene, or, as they 
termed it, cinnamol, were heated in sealed tubes to 200° for half 
an hour, the styrol solidified completely, while the cinnamol lost 
none of its mobility. They remark on this point :—“ This research 
appears at the first glance to decisively negative the opinion 
that styrol and cinnamol are identical. If, however, it be borne 
in mind that the product obtaimed by distillation with lme 
certainly contained other compounds in addition to cinnamol, 
while that prepared by the action of baryta could not, on 
account of its small quantity, be examined in this respect, we 
must conclude that a definite answer to this question can only 
be given by future investigations.” ©° Hempel now found that a 
hydrocarbon which behaves in a precisely similar manner to 
styrol is formed when the vapour of cinnamic acid is passed 
through a red-hot tube, as well as by the distillation of copper 
cinnamate,’ and also by the slow distillation of free cimnamic 


acid, C,H,.CH—CH.CO,H® 


1 Ann. Chem. Pharm. xxxi. 265. 2 Ibid. liii, 323. 
3 Jbid. liii. 321. 4 Ann. Chim. Phys. [8], i. 96. 
5 Compt. Rend. xxi. 1376. § Ann. Chem. Pharm. liii. 289. 


7 Ibid. lix. 316. 8 Miller, ibid. clxxxix. 338. 


28 AROMATIC COMPOUNDS. 


Berthelot, on the other hand, observed that cinnamol is 
optically inactive, while styrol is levo-rotatory.1 This appeared 
remarkable, inasmuch as it does not contain an asymmetric 
carbon atom, and van’t Hoff proved that the hydrocarbon obtained 
from styrax contains varying quantities of an impurity, to which 
it owes its rotatory power.? 

Styrol or cinnamol is phenylethylene, and is thus best named 
styrolene. It has been prepared by a number of different re- 
actions in addition to the methods already mentioned. 

Glénard and Boudault obtained by the dry distillation of 
dragon’s blood, dracyl, which was subsequently recognized as 
toluene (Part III. page 60) and draconyl, which, according to 
Hofmann and Blyth, is identical with metastyrol. Botsch found 
that, when dragon’s blood is distilled with zinc dust, 66 per cent. of 
styrolene are formed, in addition to ethylbenzene, a little toluene, 
and a smaller quantity of higher boiling substance.® 

Berthelot obtained it, together with benzene and other hydro- 
carbons, by heating acetylene to the softening point of glass,* and 
by passing a mixture of ethylene and benzene through a red-hot 
tube ;° he also discovered it in coal-tar.6 Thorpe found that it is 
also formed when secondary styrolyl bromide, C,H,.CHBr.CH, 
is distilled or heated with alcohol potash (Part V. page 9). 

It was formerly prepared by the distillation of liquid styrax 
with water, to which sodium carbonate was added to prevent any 
cinnamic acid passing over (Simon). It is now obtained by the 
slow distillation of cinnamic acid, which is manufactured on the 
large scale. When cinnamic acid is allowed to stand for some 
days in contact with the most concentrated hydrobromic acid, 
phenylbromopropionic acid, C,H,.CHBr.CH,.CO,.H, is formed, 
and this is decomposed by sodium carbonate solution with forma- 
tion of styrolene. A still better yield is obtamed when phenyliodo- 
propionic acid, which is prepared in a similar manner, is boiled 
with sodium carbonate solution.” 

Properties—Styrolene is a strongly refractive liquid, which has 
an aromatic odour, boils at 144°5 and has a sp. gr. of 0°925 
at 0°. It yields benzoic acid on oxidation (Blyth and Hofmann). 


1 Miller, Ann. Chem. Pharm. exli. 378. 

2 Ber, Deutsch. Chem. Ges. ix. 5 and 1839; Krakau, bid. xi. 1260. 
3 Monatshefte f. Chem. i. 609. 

4 Ann. Chem. Pharm. exli. 181. 

5 Ibid. exlii. 257. 

6 Ibid. Suppl. iii. 368. 

7 Fittig and Binder, <bid. excv. 187. 


. STYROLENE ALCOHOL. 29 


Metastyrolene. This polymeric modification is gradually formed 
when pure styrolene is allowed to stand, more rapidly at 200°, 
or when it is treated with concentrated sulphuric acid It 
is a vitreous mass, which is strongly refractive, and is converted 
on distillation into styrolene, 

Polystyrolene, (C,H,),, is formed, together with other products, 
by the dry distillation of calcium cinnamate,? by passing styrolene 
dibromide over heated lime,’ and, together with styrolene, by the 
gradual distillation of cinnamic acid (Miller). It crystallizes 
from ether or alcohol in tablets, melting at 119°. 

Distyrolene, C,,H,,, was obtained by Erlenmeyer by heating 
cinnamic acid to 150°—240° with hydrobromic acid ; he found that 
hydrochloric and dilute sulphuric acids have the same action, and 
that it is also formed by heating styrolene with hydrochloric acid 
to 170°.4 Fittig prepared it, together with distyrolenic acid, 
C,,H,,0,, by boiling cinnamie acid with sulphuric acid, which was 
diluted with one or one and a half volumes of water.® It is a 
liquid, which boils at 310°—812°, yields benzoic acid on oxidation, 
and combines with bromine to form distyrolene bromide, C,,H,,Brz, 
which crystallizes in loose masses of needles. When distyrolene 
is kept for some time at the boiling-point, it decomposes with 
formation of toluene, styrolene, isopropylbenzene, and other high- 
boiling hydrocarbons, It is probably a diphenylbutylene of the 
following constitution (Fittig) : 

Jos 
eebnietey TLN. 
C,H, 


Styrolene forms substitution products, and also, as an olefine, 
addition products. . 

2288 Styrolene alcohol, C,H;.CH(OH)CH,OH. This com- 
pound, which is also known as phenylglycol, is most easily 
prepared by boiling styrolene bromide for three or four days 
with one molecule of potassium carbonate, dissolved in four 
parts of water ; the monobromostyrolene, which is simultaneously 
formed, is then distilled off, and the glycol extracted from 
the residue with ether. On evaporation it is left as an oil, 
which gradually crystallizes. It is readily soluble in water, 


1 Berthelot, Bull. Soc. Chim. vi. 296. 

2 Engler and Leist, Ber. Deutsch. Chem. Ges. vi. 254. 
3 Radziszewski, tbid. vi. 492. 

4 Ann. Chem. Pharm. cxxxv. 122. 

5 Ibid. cexvi. 187. 


30 AROMATIC COMPOUNDS. 





alcohol, ether, &c., and is best crystallized from a hot mixture of 
benzene and petroleum spirit, from which it separates on cooling 
in fine silky needles, melting at 67°—68°. 

Styrolene alcohol boils at 272°—274°, and is converted by 
boiling with dilute sulphuric acid into phenylacetaldehyde, 
C,H;.CH,.CHO, an intermediate product, distyrolene droxide, 
being first formed, especially when the acid employed is weak ; 
this forms a thick, oily liquid, which boils at 250° under a 
pressure of 50 mm., and probably has the following constitution : 


O 
C,H, CH,CHC | >CH.CH, C,H, 


Chromic acid oxidizes the alcohol to benzaldehyde and benzoic 
acid; nitric acid, on the other hand, converts it first into 
benzoylmethyl alcohol, C,H,;.CO.CH,.OH. 

Styrolene chloride, C,H;.C,H,Cl,, is formed by the direct com- 
bination of styrolene with chlorine, but is difficult to purify since 
substitution products are simultaneously formed. It is a thick, 
oily liquid, which decomposes on distillation, and is scarcely 
soluble in water, but imparts to it a very characteristic penetrat- 
ing smell and taste, resembling those of the oils of lemons and 
juniper berries (Blyth and Hofmann). 

Styrolene bromide, C,H,.C,H,Br,, was also prepared by Blyth 
and Hofmann, and has the same characteristic smell and taste as 
the chloride. It is best obtained by mixing styrolene with an 
equal volume of chloroform,? or with two volumes of ether,? and 
adding the calculated quantity of bromine to the well-cooled 
liquid. It may also be prepared by adding bromine gradually 
to hot ethylbenzene,‘ and purifying the product by recrystalliza- 
tion (Zincke). It crystallizes from alcohol in small plates or 
broad needles, melting at 74°—74°5. 

Styrolene vodide, C,H;.C,H,1,, was obtained by Berthelot, by 
agitating styrolene with a solution of iodine in potassium iodide. 
It forms crystals, which are soluble in ether, and readily decom- 
pose into iodine and metastyrolene.° 

Styrolene acetate, C,H;.C,H,(C,H,0,),, is prepared by heating 

1 Zincke, Ann. Chem. Pharm. eexvi. 206. 

2 Glaser, ibid. cliv. 154. 

3 Zincke, ibid. ccxvi. 288. 

4 Radziszewski, Ber. Deutsch. Chem. Ges. vi. 493; Friedel and Balsohn, Bull. 


Soc. Chim. xxxv. 55. 
DSL DiaV is D's Wis Dias 


ORTHOVINYLANISOL. 31 


the bromide with potassium acetate and glacial acetic acid, or 
the alcohol with acetic anhydride. It is an oily, odourless liquid, 
boiling at 274° (Zincke). 

 Styrolene benzoate, C,H;.C,H,.(C-H,O,)., crystallizes from hot 
alcohol or benzene in small, lustrous needles, which melt at 96° 
—97*, and sublime without decomposition (Zincke). 

Styrolene thiocyanate, C,H,.C,H,(SCN),, is prepared by boiling 
the bromide with an alcoholic solution of potassium thiocyanate. 
It crystallizes from dilute alcohol in yellowish white needles, 
which melt at 101°—102°. It volatilizes with steam, to which 
it imparts a peculiar sharp smell, and causes a violent burning 
pain when placed on sensitive portions of the skin. It combines 
with benzene to form a compound, which crystallizes in long 
needles, loses benzene in the air, and melts at 62°. 


SUBSTITUTION PRODUCTS OF STYROLENE. 


2289 The hydrogen of both the nucleus and the side-chain in 
styrolene can be replaced, but many substitution derivatives are 
not prepared from the hydrocarbon, but by ditferent reactions. 
The only known derivatives in which the hydrogen of the 
nucleus has been replaced are nitrostyrolene and the methyl 
ether of the still unknown hydroxystyrolene. The latter will be 
described first, while nitrostyrolene will be treated along with 
the other nitro-substitution products. 

Orthovinylanisol, (CH,0)C,H,.CH—CH,, is formed by heating 
orthomethyoxyphenylacrylic acid, (CH,0O)C,H,.CH—CH.CO,H, 
or better by combining the latter with iodine, and treating the 
product with a cold solution of sodium carbonate. It is a liquid, 
which has a similar odour to the higher-boiling portion of coal- 
tar naphtha, but fainter and more agreeable. It does not 
solidify in a freezing mixture, and boils at about 195°—200°, the 
greater portion being thereby converted into a polymeric modifi- 
cation, which can be obtained by heating for an hour at 150° in 
the form of a transparent, vitreous mass, which is again con- 
verted into the monomolecular variety on more strongly heating, 

Paravinylanisol has been prepared by Perkin from para- 
methoxyphenylacrylic acid ; it has an odour resembling that of 
fennel, solidifies on cooling to a crystalline mass, and boils at 

1 Nagel, Ann. Chem. Pharm. cexvi. 323. 


32 AROMATIC COMPOUNDS. 


about 204°—205°, a partial polymerization taking place, this 
being completely effected when it is heated to 150° for several 
hours.! 

This compound is the lower homologue of anethol, which 
forms the chief constituent of oil of anise and other similar 
oils. 

Hesperetol, (CH,0)C,H,(OH)CH—CH,, is formed by the dry 
distillation of the hydrated calcium salt of hesperitic acid, 
(CH,0)C,H,(OH)C,H,.CO,H, and forms a crystalline mass, 
which melts at 57°, and has an agreeable odour recalling those 
of both guaiacol and styrolene. It forms a splendid carmine-red 
solution in sulphuric acid.? 

a-Phenylchlorethylene or Phenylvinylchloride, C,H;.CH—CHCI, 
was first obtained by Stenhouse in an impure condition by the 
distillation of cinnamic acid with bleaching-powder solution.* 
Glaser, who named it §-chlorstyrol, prepared it by the action of 
chlorine on a dilute solution of sodium cinnamate, and by 
heating phenylchlorolactic acid, C,H,.C,H,Cl(OH)CO,H, with 
water to 200°—220°* It is also formed by the action of 
sodium carbonate solution on phenyldichloropropionic acid, 
C,H,;.CHC1.CHCLCO,H, and when phenylacetaldehyde is 
treated with phosphorus pentachloride, and the product of 
this reaction, a-phenylethidene chloride, C,H;.CH,.CHCL, a liquid 
with a sharp, turpentine-like odour, heated with alcoholic 
potash.® 

a-Phenylchlorethylene is a liquid which has a pleasant hya- 
cinth-like odour, and boils at 199°. When it is heated with an 
alcoholic solution of sodium ethylate, phenylvinyl ethyl ether, 
C,H,.,CH—CH.OC,H,, is formed as a liquid which boils at 
217°, and decomposes on heating with water into ethyl alcohol 
and phenylacetaldehyde (Erlenmeyer). 

B-Phenylchlorethylene, C,H,.CC1l=CH,. When methylphenyl- 
ketone is treated with phosphorus pentachloride, B-phenylethi- 
dene chloride, C,H,.CCl,CHs, is formed, and decomposes on 
distillation into hydrochloric acid and §-phenylchlorethylene. 
This is a liquid, which boils at 190° and is converted into 


1 Perkin, Journ. Chem. Soc. 1877, ii. 608 ; 1878, i. 211. 
2 Tiemann and Will, Ber. Dewtsch. Chem. Ges. xiv. 967. 
3 Ann. Chem. Pharm. lv. 3; vii. 79. 

4 Ibid. cliv. 164. 

5 Erlenmeyer, Ber. Deutsch. Chem. Ges. xiv. 1867. 

6 Forer, ibid. xvii. 982. 

7 Friedel, Bull. Soc. Chim. i. 7. 


PHENYLVINYL BROMIDE. 33 





phenylacetylene, C,H,.C=CH, by heating to 120° with alcoholic 
potash, while the a-compound loses no chlorine even at 200° 
when subjected to the same treatment, but is only partially 
converted into a resinous mass (Glaser). <A similar relation is 
shown by the two chloropropylenes.! 

a-Phenylbromethylene or Phenylvinyl bromide,C,H,.CH—CHBr, 
is formed when phenyldibromopropionic acid, C,H,.CHBr.CHBr. 
CO,H, is boiled with water (Glaser), and is an oily liquid, which 
has a pleasant odour, resembling that of hyacinths, and solidi- 
fies at a low temperature to a dazzling white, crystalline mass, 
melting at + 7°. It boils at 219°—221°, a small quantity. of 
hydrobromic acid being evolved, and combines with bromine to 
form bromostyrolene dibromide, C,H;.CHBr.CHBr,, which crystal- 
lizes from petroleum-ether in long needles, melting at 37°—38° 

B-Phenylbromethylene, C,H,.CBr—CH,, is obtained by the 
action of boiling alcoholic potash on styrolene bromide. It is 
a heavy oily liquid, the vapour of which produces a flow of 
tears, and decomposes on distillation, even under diminished 
pressure (Glaser). When it is heated to 180° with water, 
methylphenylketone, C,H;.CO.CH,, is formed, while the action 
of sodium and carbon dioxide yields a mixture of phenylpropiolic 
and phenylpropionic acids, but, contrary to the statement of 
Swarts, no cinnamic acid.® 

2290 a-Phenylnitro-ethylene, C,H;.CH—CHNO,, was first pre- 
pared by Simon by the direct action of concentrated nitric acid 
on styrol and was named by him zitrostyrol, its composition 
being subsequently determined by Blyth and Hofmann. The 
same compound is formed when equal molecules of nitromethane 
and benzaldehyde are heated to 160° with a little zinc chloride : * 


C,H,.CHO + CH,NO, = C,H,.CH—CHNO, + H,0. 


It has also been obtained by the action of concentrated nitric 
acid on phenylcrotonic acid,’ C,H;.CH—CH.CH,.CO,H. 

It crystallizes from alcohol in splendid, yellow, rhombic 
prisms, which melt at 58°. It has a strong smell and taste of 
cinnamon, produces burns and blisters on the skin, like oil of 
mustard, is readily volatile with steam, and in the form of 


1 Erlenmeyer, Ber. Deutsch. Chem. Ges. xii. 1609. 
2 Fittig and Binder, Ann, Chem. Pharm. excv. 114. 
3 Erlenmeyer, Ber. Deutsch. Chem. Ges, xvi, 152. 

4 Priebs, Ann. Chem. Pharm. cexxv. 319. 

> H. Erdmann, Ber. Deutsch. Chem, Ges, xvii. 412. 


34 AROMATIC COMPOUNDS. 


vapour attacks the eyes and nose most violently. In the com- 
pact state it scarcely dissolves in caustic soda, but when finely 
divided it dissolves completely and is reprecipitated by acids. 
When sodium nitrite and then dilute sulphuric acid are added to 
the alkaline solution, the nitrolic acid reaction takes place, being 
probably caused by liberation of nitromethane. On heating to 
100° with concentrated hydrochloric acid, it decomposes with 
- formation of phenylchloracetic acid and hydroxylamine : 


C,H,.CH—CHNO, + H,O + HCl = C,H,.CHCLCH,.CO,H 
+ N(OH)H,. 


Crystals of a-phenylnitro-ethylene change in the light to a 
dull white, polymeric body, which crystallizes from hot alcohol 
in rhombic plates or needles with a satin lustre. This sub- 
stance is not identical with the nitrometastyrol, which Blyth 
and Hofmann prepared by the nitration of metastyrol and 
described as an amorphous powder, insoluble in alcohol. 

Phenylnitro-ethylene chloride, C,H,;.CHCLCHCI(NO,), is pre- 
pared by passing chlorine into a cooled solution of phenylnitro- 
ethylene in chloroform. On the evaporation of the latter, it 
remains as a thick oil, which has a penetrating odour, resembling 
when dilute that of pippins. On standing for some time, large 
lustrous crystals are deposited, which are extremely soluble in 
ether ‘and chloroform, and are again left on evaporation as an oil, 
which solidifies, when placed in contact with a fragment of the 
original crystals, to a mass, which melts at 30°. 

Cold caustic soda solution converts it into phenylchloronitro- 
ethylene, C,H;.CCL=CHNO,, which crystallizes from petroleum 
spirit in lustrous, golden-yellow plates or tablets, which have a 
characteristic odour, melt at 48°—49° and, when finely divided, 
dissolve in alkalis, thus proving that the group CHNO, is 
present (Vol. III. Part I. p. 188). 

Phenylmitro-ethylene bromide, C,H,.CHBr.CHBr(NO,), is best 
obtained by bringing the two constituents together in carbon 
disulphide solution. On evaporation it separates in splendid, 
monosymmetric crystals, which have a vitreous lustre, melt at 
86° and are soluble in alkalis. Caustic soda converts it into 
phenylbromonitro-ethylene, C,H;.CBr—CHNO,, which crystallizes 
from petroleum-spirit in golden-yellow, iridescent needles or 
plates, which melt at 67°-—68° and have a characteristic odour, 
slightly resembling that of hay. 


THE NITROSTYROLENES. 35 


2291 The Nitrophenylethylenes or Nitrostyrolenes, C,H,(NO,) 
CH—CH,, are formed by the action of hot carbonate of sodium 
solution on the nitrophenylbromopropionic acids, C,H,(NO,) 
CHBr.CH,.CO,H, or by heating the lactones of the nitrophenyl- 
lactic acids, which are also obtained from these bodies : 


By 
C.H,(NO,)CH CO = C,H,(NO,)CH=CH, + CO,, 


ao 


Orthonitrostyrolene is an oil, which is volatile with steam, has 
a characteristic odour and solidifies on cooling to a splendid 
crystalline mass, melting at 12°—13°5. It is coloured blue 
when heated with concentrated sulphuric acid and forms a 
crystalline dibromide, melting at 52°. 

Metanitrostyrolene has an agreeable, cinnamon-like smell and 
melts at —5°; its dibromide forms crystals, which melt at 
18°—79°? 

Paramitrostyrolene crystallizes from petroleum-spirit in yel- 
lowish, strongly refractive prisms, which melt at 29°, smell like 
oil of cinnamon and have a burning, bitter, but slightly sweet 
taste. It changes into an insoluble polymeric modification on 
standing. Its dibromide melts at 72°—73° 

Paranitrophenylnitro-ethylene, C,A4(NO,)CH—CHNO,, which 
is also known as w-4-dinitrostyrol, 1s easily prepared by the 
elimination of carbon dioxide from paradinitro-cinnamic acid,* 
C,H,(NO,)CH—C(NO,)CO,H, and is also formed, together 
with the ortho-compound, by the nitration of phenylnitro- 
ethylene (Priebs). It crystallizes from acetone in yellow plates 
and from alcohol in needles, which melt at 199°, sublime when 
carefully heated and are volatile with steam. 

It is oxidized to paranitrobenzoic acid by chromic acid solu- 
tion and is decomposed by warming with sulphuric acid, carbon 
monoxide being evolved and paranitrobenzaldehyde and hydro- 
xylamine sulphate formed : 


C,H,(NO,)CH—CHNO, + H,O = C,H,(NO,)CHO 4 
N(OH)H, + CO. 


These then combine to some extent to form paranitrobenz- 
aldoxime. 
1 Kinhorn, Ber. Deutsch. Chem. Ges. xvi. 2218. 


2 Prausnitz, ibid. xvii. 597. 3 Basler, 7bid. xvii. 3005. 
4 Friedlander and Mahly, zbid. xvi. 848 ; Ann. Chem. Pharm. ccxxix. 224. 


36 AROMATIC COMPOUNDS. 


Paranitrophenylnitro-ethylene bromide, C,H,(NO,)CHBr.CHBr 
(NO,), forms colourless, lustrous plates, melting at 102°—108°. 

Metanitrophenylnitro-ethylene or w-3-Dinitrostyrolene, is a pro- 
duct of the decomposition of the very unstable metadinitro- 
cinnamic acid and crystallizes from alcohol in yellowish plates, 
which melt at 122°. It behaves towards chromic and sulphuric 
acids similarly to the para-compound. If it be dissolved in 
alcohol and treated successively with caustic soda solution and 
bromine water, metanitrophenylethoxydibromonitro-ethane, C,H, 
(NO,)CH(OC,H,)CBr,N O,, is formed, and is deposited in lustrous 
plates, melting at 98°—99°1 

Orthonitrophenylnitro-ethylene is more readily soluble in alcohol 
than the para-compound and crystallizes in distorted yellow 
needles, which melt at 106°—107° and are volatile with steam. 
Alkaline permanganate oxidizes it to orthonitrobenzoic acid. 
Its dibromide forms white needles, melting at 90°—90°5 (Preibs). 

Orthonitrophenylchlorethylene or Orthonitrophenylvinyl chloride, 
C,H,(NO,)CH—CHCI, is formed by the action of hypochlorous 


acid on sodium orthonitro-cinnamate : 


C,H,(NO,)CH—CH.CO,Na + ClIOH = C,H,(NO,)CH—CHCI + 
CO,NaH. 


It crystallizes from hot alcohol in lustrous, yellowish needles, 
or prisms, melting at 58°—59°, has a pleasant odour and produces 
a burning pain when placed on the skin. 

Orthamidophenylvinyl chloride, C,H, NH,)CH—CHCIl, is 
obtained by the reduction of the preceding compound with tin 
and hydrochloric acid. It is slightly soluble in cold, more 
readily in hot water and alcohol and crystallizes in prisms, which 
have a peculiar but not unpleasant smell.2 On heating with 
sodium ethylate it is converted into indol. 

2292 Indol, C,H,N, was first prepared by Baeyer by heating 
oxindol, C,H,NO (p. 21), with zinc dust.2 He then found that 
it can also be obtained directly from indigo by heating with 
tin, or zinc, and hydrochloric acid, and distilling the yellow 
reduction product with zinc dust, and he therefore looked 
upon it as the mother substance of indigo.4 It was shortly 
afterwards prepared by Baeyer and Emmerling by heating 
orthonitrocinnamic acid with caustic potash and iron filings; ° 


1 Eriedlainder and Lazarus, Ber. Deutsch. Chem. Gies. ecxxix. 238. 

2 Lipp, ibid. xvii. 1070. | 3 Ann. Chem. Pharm. exl. 295. 
4 Ber. Deutsch. Chem. Ges. i. 17; Ann. Chem. Pharm. Suppl. vii. 56. 
5 Ber. Deutsch. Chem. Ges. ii. 679. 


INDOL. 37 





and Baeyer and Caro found that it is formed in small quantity 
when aniline is passed through a red-hot tube.1 Methylethyl- 
aniline and diethylaniline give a somewhat better yield, and a 
still larger amount is obtained when dimethylorthotoluidine 
and especially diethylorthotoluidine, are employed, while diethyl- 
paratoluidine does not give a trace.2 It is formed in large 
quantity, however, when the vapour of cumidine, or orthamido- 
isopropylbenzene, C,H,(NH,)CH(CH,),, 1s passed over heated 
lead oxide,? and is also obtained when oxalorthotoluidic acid, 
CH,.C,H,.NH.CO.CO.OH, is heated with zine dust, or when its 
barium salt is submitted to dry distillation.‘ 

It is derived from oxindol, the anhydride of orthamidopheny]l- 
acetic acid, by a simple elimination of oxygen ; according to this 
reaction its constitution could be expressed by any one of the 
following formule : 


Scu “Now. 


OH 
Or OTe si ee 
BC, AN Ra 
Its formation from orthonitro-cinnamic acid is in favour of the 
last of these: 


CH=CH.CO,H CH 
olin Pees cst SCM OG. O- 

no SNS piles 
2 


The careful study of its reactions has proved that it contains 
the imido-group and it can therefore be looked upon as the anhy- 
dride of the unknown orthamidophenylvinyl alcohol, which, like 
other similar ortho-amido-compounds does not exist in the free 
state. Its chloride, however, is known, and has already been de- 
scribed, and Lipp has shown that this is converted into indol 
when heated with sodium ethylate.6 Orthamidophenylvinyl 
ether is probably first formed, but decomposes immediately into 
ethyl alcohol and indol : 


CH—CHCI //CH=CH.00=H, 
+Na00,H,=C,H,~ ‘Sr {NaCl 


C, BN 
_ SHEOH OC,H, 
Cy BN NH, \ Leo BK 


1 Ber. Deutsch. Chem. Ges. x. 692. 2 bid. x. 1262. 
3 Fileti, ibid. xvi. 2928. 

* Mauthner and Suida, Monatsh. Chem. vii. 230. 

5 Ber. Deutsch. Chem. Ges. xvii. 1067. 


ae + HO.O,H, 


38 AROMATIC COMPOUNDS. 


It is also formed by the fusion of albuminoid substances with 
caustic potash, and by the pancreatic fermentation of the same,” 
so that it occurs, together with its homologue skatol, C,H,N, in 
human excrement; it is only present however in small quantity, 
since it is for the most part converted into indoxylsulphuric acid, 
C,H,NSO,H, which is excreted with the urine (p. 40). 

Indol is readily soluble in alcohol, ether and hydrocarbons, and 
tolerably in hot water, from which it separates on cooling in oily 
drops, which subsequently form plates,.similar to those of benzoic 
acid. It crystallizes from petroleum-spirit in large plates, which 
melt at 52° and have a satin lustre. It is volatile with steam 
and boils with partial decomposition at 245°—246°, so that the 
determination of its vapour density always gives high values, 
4°33— 4°62 instead of 4°05. 

It possesses a characteristic, disagreeable and persistent odour. 
When an aqueous solution of indol is treated with sodium nitrite 
solution acidified with sulphuric acid, or with a little red 
fuming nitric acid, a red precipitate consisting of microscopic crys- 
tals is formed, which has the composition C,,H,,(NO)N,.NO,H 
(Nencki),* while large red needles of a different compound 
are deposited when nitrogen trioxide is passed into an alcoholic 
solution. A pine splinter moistened with hydrochloric acid is 
coloured deep cherry-red by a solution or the vapour of indol 
(Baeyer). 

Indol suspended in water is partly oxidized to indigo blue, 
C,,H,)N,0,, by the action of air containing ozone, while the 
remainder is converted into a resinous mass (Nencki). 

Indol is a weak base and forms a salt with hydrochloric acid, 
which is only slightly soluble and is decomposed by boiling with 
water. 

Indol picrate, C,5H,N.C,H,(NO,),0. This characteristic com- 
pound is formed when its constituents are brought together 
in benzene solution. It crystallizes in long, red needles, which 
are scarcely soluble in petroleum-spirit, slightly in cold but 
readily in hot benzene and are decomposed by ammonia.? 

(2293 Methylindol, C,H,N.CH,. Pyroracemic acid combines 
with methylphenylhydrazine to form methylphenylhydrazine- 


1 Engler and Janecke, Ber. Deutsch. Chem. Ges. ix. 1411; Nencki, Jowrn. 
Prakt, Chem. [2], xvii. 98. 

* Nencki, Ber. Deutsch. Chem. Ges. vii. 1598; viii. 836; Brieger, Hoppe- 
Seyler’s Zeztschr. iii. 141. 

3 Nencki, Ber. Deutsch. Chem. Gs, viii. 1517. 

AL bud, vu 722. 

5 Baeyer and Caro, ibid. x. 1263 ; Baeyer, zbid. xii. 1814. 


METHYL INDOL. 39 


pyroracemic acid, which is quantitatively decomposed by hydro- 
chloric acid into ammonia and methylindolcarboxylic acid : 


CH, 

O,H,. N—N=C = OH  SC.0O,H + NH, 
ag N- 
GE CO.H | 


CH, 


This substance decomposes on continued heating into carbon- 
dioxide and methylindol ; the latter is an oily liquid, which boils 
at 239°, does not solidify at —20° and smells like the aromatic 
bases and not like indol. It dissolves in concentrated hydro- 
chloric acid and is reprecipitated by water; it behaves towards 
fuming nitric acid and nitrous acid in the same way as indol, and 
colours a pine splinter moistened with hydrochloric acid a deep 
reddish violet. 

Methylindol prerate, C,H,N(CH,)C,H,(NO,),0, is readily 
soluble in hot benzene, less readily in ether and crystallizes from 
the latter in splendid dark-red prisms, which melt at 150° and 
are decomposed by water, especially on warming. 

Lithylindol, C;H,N.C,H,, has been prepared from ethylphenyl- 
hydrazine; it boils at about 247° and can scarcely be dis- 
tinguished by its other properties from methylindol. 

Phenylindol, C3H,N.C,H,, is a heavy oil, which has been 
obtained from diphenylhydrazine; it colours an acidified pine 
splinter a deep bluish violet.t 

The following indols have been prepared from the methyl- and 
ethyl-derivatives of the tolylhydrazines :? 

Boiling-point. 

Methylorthotolindol, C,H,(CH,)N.CH, .. . -—— 

Methylparatolindol, C,H,(CH,)NCH, . . . . 242°—245° 

Ethylparatolindol, C,H,(CH,)NC,H, . . . . 253°—255° 


Benzylindol, Cs;H,N.CH,.C,H;, was obtained from benzyl- 
aniline, by converting this into the hydrazine and treating it as 
described above. It crystallizes from alcohol in compact needles, 
which melt at 44°5 and only have a faint smell. It gives a 
reddish violet colouration. with the pine-wood test. 

Acetylindol, C;1,NCO.CH,, is formed by heating indol with 


1 Fischer and Hess, Ber. Deutsch. Chem. Ges. xvii. 589. 
2 Hegel, Ann. Chem. Pharm. ccxxxii, 214. 
3 Antrick, zbid. ccxxvii. 360. 


269 


40 AROMATIC COMPOUNDS. 


acetic anhydride ; it is readily soluble in benzene and crystallizes 
from hot water in long needles, which melt at 182°—183° and 
sublime in four-sided, truncated pyramids. 

2294 Indoxyl, C,H,NO, was first observed as a product of the 
decomposition of indoxylsulphuric acid.? Baeyer then obtained 
it from indoxylic acid, C,H,NO(CO,H), which is formed by 
the reduction of orthonitrophenylpropiolic acid, C,H,(NO,) 
C=C.CO,H, and decomposes into carbon dioxide and indoxyl on 
boiling with water.? It is a brown oil, which is not volatile 
with steam, is readily converted into a resinous mass and dissolves 
slightly in hot water, forming a solution which shows a yellowish 
green fluorescence. It is simultaneously an acid and a base; its 
alkaline solution absorbs oxygen from the air with formation of 
indigo-blue, which is also formed when ferric chloride is added to 
its solution in hydrochloric acid. 

Nitroso-indoayl, C,5H,(NO)NO, is obtained in fine, yellowish 
needles, when indoxyl is treated with sodium nitrite and then 
dilute hydrochloric acid.* 

Ethylindoxyl, C,H,NO(C,H,), is formed when ethylindoxylic 
acid, C,H,.NO(C,H,)CO,H, is heated and is a colourless liquid, 
which is volatile with steam, smells like indol and colours pine- 
wood moistened with hydrochloric acid a brownish red. It also 
forms a nitrosamine, crystallizing in yellowish needles, and is 
converted into indigo-blue by oxidation. 

Phenylazo-indoxyl, C,,H,,N,0, is obtained by adding a solution 
of diazobenzene chloride to an aqueous solution of indoxyl. It 
crystallizes from alcohol in thick, orange-coloured prisms, which 
have a fine yellowish green, metallic lustre and melt at 236° with 
decomposition ; it forms a reddish brown solution in caustic soda, 
from which it is reprecipitated by carbon dioxide. 

Indoxylsulphurie acid, C,H,N.O.SO,0H. After Schunck had 
proved that indigo is not contained as such in the plants from 
which it is obtained, but is formed by the decomposition of a 
glucoside, which he named indican, he also endeavoured to 
isolate the substance which yields the indigo which is sometimes 
found in urine. He was unable to obtain it in the pure state, 
but thought it probable that it was also a glucoside and perhaps 
identical with indican.2 According to Hoppe-Seyler, it is an 
invariable constituent of the urine of Herbivora, and always 


1 Baeyer, Ber. Deutsch. Chem. Ges. xii. 1314. 

2 Baumann and Tiemann, zbid. xii. 1098. 

3 Baeyer, ibid. xiv. 1741. 4 Ibid. xvi. 2188. 
5 Mem. Manchester Lit. Phil. Soc. xiv. 239; Jahresber. Chem. 1857, 564. 


INDOXYLSULPHURIC ACID. 41 





occurs, although in very small quantity, in normal human urine, 
but in larger quantities during certain diseases.1_ It increases 
during a diet of albumen, and since this food yields indol 
when subjected to the pancreatic fermentation, the latter ap- 
peared to be the source of the “urine-indican,” a supposition 
which was confirmed by the fact that the amount of urime- 
indican increased largely when indol was administered.” 
Baumann then showed that the substance found in the urine 
is quite different from vegetable indican.2 He and Brieger 
succeeded in obtaining it in larger quantity from the urine of a 
dog, to which 15 grammes of indol were administered in the 
course of five days. They found that it is the potassium salt of 
indoxylsulphuric acid, and investigated it more thoroughly.® 
Baeyer then prepared it by heating a solution of indoxyl with 
potassium disulphate.® It is readily soluble in water, slightly in 
cold alcohol and crystallizes from hot alcohol in lustrous plates 
or tablets, which decompose on heating with dilute acids into 
indoxyl and acid potassium sulphate, but are not attacked by 
caustic potash solution even at 170°. When the dry salt is heated, 
indigo-blue sublimes, and this is quantitatively formed when the 
solution is warmed with ferric chloride and hydrochloric acid 
(Baumann and Tiemann). 

Indoxyl contains the imido-group, since it forms a nitrosamine, 
and also a hydroxyl-group, as is proved by the formation of 
indoxylsulphuric acid. The constitutions of the compounds 
mentioned above are expressed by the following formule : 


Tndoxyl. Indoxylic acid. 
OH. 
| 
yo oH So.co,E 
AK Br aN NH axe ie 
ae Indoxylsulphuric acid. 
OC,H, O.S0,.0H 


| | 
EG bie 
HZ »> oS \ 
INGE pao C, H, Nee yet 


1 Arch. Pathol. Anatomie, xxvii. 388. 

2 Jaffé, Centralblatt med. Wissenschaft, 1872, 2. 
3 Pfliiger’ s Arch. xiii. 291. 

4 Hoppe-Seyler’s Zeitschr. iii. 254. 

5 Ber. Deutsch. Chem. Ges. xii, 1098, 

6 Ibid, xiv. 1745. 


42 AROMATIC COMPOUNDS. 


Nitroso-indoxy]l. Phenylazo-indoxyl. 

OH OH. 

‘ l 
#¢ Now nf SoH 
ae a aN 3 a 

H 

NO N—NC.H; 


Indoxyl can therefore be looked upon as the anhydride of 
orthamidostyrolene alcohol. 

2295 The Indogenides. Baeyer has given this name to the 
compounds which are formed by the action of aldehydes or 
ketonic acids upon indoxyl or indoxylcarboxylic acid, as, for 
example : 


pag ha of Benzaldehyde. Indogenide of maar re aa 
CO 
Te "Soe —cHoH, oa Yoae’ 
ANE NG G5 H 


In order to explain their formation, Baeyer assumes that the 
‘aindoxyl passes first into pseudo-indoxyl, which is incapable of 
‘existence in the free state, and that this reacts in the case of 
pyroracemic acid, for example, in the following way : 


CO CH, 


Paes uf a 
CHK poor “i ee a 


JAH 
on’. HON Gee Aa ris 
AW ive *\ co, P 


Pseudo-isatoxime, which was formerly known as nitroso-indoxyl, 
is formed in a similar manner by the action of nitrous acid. These 
compounds will be subsequently described. They contain the 
divalent radical zndogen, and indigo-blue itself is di-indogen, 
which is formed from indoxyl by the oxidation of the pseudo- 
indoxyl which 1s first formed : 


ve 
C,H 


eet aN x 
HK on PBs +20 =C HK oa Pools 


+ 2H,0. 


MANDELIC ACID. 43 





PHENYLGLYCOLYL-COMPOUNDS. 


2296 Phenylhydroxyacetic acid, C,H;.CH(OH)CO,H, was first 
prepared by Winckler by heating extract of bitter almonds with 
hydrochloric acid, and was called mandelic acid.1_ This reaction 
is the first instance of the synthesis of a hydroxy-acid from 
hydrocyanic acid and an aldehyde. Liebig, who considered the 
discovery of this acid as one of the most important additions 
which had recently been made to organic chemistry, writes upon 
its formation : 

“ Mandelic acid is formed when hydrochloric acid is evaporated 
with a mixture of hydrocyanic acid and benzoyl hydride; in ad- 
dition to this product ammonia is formed and remains combined 
with the hydrochloric acid. 

“The nitrogen of the hydrocyanic acid must be contained in 
the ammonia and its other constituents in the mandelic acid. It 
is already well known, that when hydrocyanic acid is decomposed 
by the action of mineral acids or strong bases, formic acid is 
formed on the one hand, and ammonia set free on the other. 

“Tf the constituents of formic acid be actually subtracted 
from the formula of mandelic acid, that of benzoyl hydride 
remains. 

“This acid is therefore built up by the combination of the 
formic acid at the moment of its formation with benzoyl 
hydride.” # 

Laurent obtained the same acid by the action of fuming 
sulphuric acid on crude oil of bitter almonds and named it 
acide formobenzoilique.2 Wohler found that it is also formed 
when amygdalin is heated with fuming nitric acid,t but Lew- 
kowitsch has shown that the acid prepared by this method is 
optically active and stands in the same relation to that obtained 
from oil of bitter almonds as levotartaric acid to ordinary 
tartaric acid.° 

Several methods have been proposed for its preparation from 
benzaldehyde and hydrocyanic acid. According to Spiegel it 


1 Ann. Chem. Pharm. xviii. 310. 2 Ibid, xviii. 319. 

3 Ann. Chim. Phys. [2], lxv. 202. 

4 Ann. Chem. Pharm. lxvi. 238. 

5 Ber, Deutsch. Chem. Ges, xvi. 1565, 1568 and 2721. 

6 Naquet and Luginin, Ann. Chem. Pharm. cxxxix. 299 ; Wallach, 77d. 
excili. 38. 


44 , AROMATIC COMPOUNDS. 





is most simply obtained by moistening rather more than one 
molecule of pure potassium cyanide with a little water, pouring 
one molecule of benzaldehyde upon it and then allowing one 
molecule of hydrochloric acid, in the form of the fuming aqueous 
acid, to drop slowly into the well-agitated and cooled mixture. 
The phenylhydroxyacetonitril, C,H,.-CH(OH)CN, thus formed is 
heated for two hours to 130°—140° with two volumes of hydro- 
chloric acid saturated at 0°, and the phenylchloracetic acid, 
C,H,.CHCLCO,H, which is the product of this reaction, finally 
converted into mandelic acid by boiling with a caustic alkali or 
an alkaline carbonate.’ 

It crystallizes in rhombic needles or large tablets, which melt 
at 118° and are readily soluble in alcohol, ether and water; 100 
parts of the last dissolve 15°97 parts at 20° (Lewkowitsch). It 
has a faint odour resembling that of sweet almonds and tastes 
strongly acid and then somewhat styptic. It is oxidized to 
benzoic acid by nitric acid, while carbon dioxide and benzal- 
dehyde are formed when its aqueous solution is boiled with 
manganese dioxide.. Benzaldehyde is also a product of its 
decomposition by dry distillation (Liebig) and is formed, accom- 
panied by formic acid, when it is heated to 130° with dilute 
sulphuric acid.” 

When a solution of mandelic acid is neutralized with cinchonin 
and concentrated, the salt of the dextro-rotatory acid is the first 
to separate out. 

Leevomandelic acid is also formed, as already mentioned, when 
amyegdalin is heated for several hours on the water-bath with 
fuming hydrochloric acid, black humus-like substances being 
also formed. The acid is extracted from the filtrate with ether. 
It forms rhombic crystals, which do not melt until 132°8 and 
are less soluble in water than the inactive acid, 100 parts only 
dissolving 8°64 parts at 20°. 

The growth of Penicilliwm glaucum in a nutritive solution 
containing the imactive acid causes its decomposition in such 
a way that the lzevo-rotatory acid is used for the building up of 
the cells, while the dextro-acid remains behind. Another fungus 
exerts exactly the opposite action and only assimilates the dextro- 
acid. 

Dextromandelic acid has the same melting-point, the same 
solubility and the same rotating power, but of the opposite sign, 


1 Naquet and Luginin, Ann. Chem. Pharm. cxl. 239. 
? Biedermann, Ber, Deutsch. Chem, Ges. xix. 638. 


SALTS OF MANDELIC ACID. 45 





as the levo-acid. When equal parts of the two modifications 
are dissolved in water and the solution concentrated, the ordin- 
ary inactive variety, melting at 118°, crystallizes out. They 
also pass into the latter when heated for thirty hours to 160°, 
a portion being decomposed with formation of benzaldehyde 
(Lewkowitsch). 

2297 Potassium phenylhydroxyacetate, C,H,O03K, is very readily 
soluble in water and alcohol, and remains on evaporation as a 
soft, friable mass somewhat resembling soap, which has hardly 
the taste of a salt but tastes and smells faintly lke sweet 
almonds, 

Barium phenylhydroxyacetate, (C,H,0,),Ba, is less soluble in 
water than the potassium salt and readily crystallizes in very 
short, thin prisms. 

Lead phenylhydroxyacetate, (C,H,O0,),Pb, is a crystalline pre- 
cipitate, scarcely soluble in water. 

Copper phenylhydroxyacetate, (C,H,0,),Cu, forms a fine, light- 
blue, almost insoluble powder. 

Silver phenylhydroxyacetate, C,H,0,Ag, is a white, crystalline 
precipitate, which is soluble in boiling water, from which it 
separates in yellowish crystals, resembling those of benzoic acid. 

Methyl phenylhydroxyacetate, C,H,0O,(CH;), is very readily 
soluble in alcohol and crystallizes from a mixture of benzene 
and petroleum spirit in small, lustrous plates, which melt at 
47° —49°} 

Ethyl phenylhydroxyacetate, C,H,.;CH(OH)CO,.C,H,;. When 
hydrochloric acid is passed into a solution of phenylhydroxy- 
acetonitril im absolute alcohol, the phenylhydroxyacetimido- 
ether separates out in needles; this substance is decomposed 
by water in the following manner: 


NHC 
C,H; CHOW) + H,O=C,H,.CH(OH)CO.OC,H, + 


Daa 5, 


NH,Cl 


Ethyl phenylhydroxyacetate is a heavy, strongly refractive 
liquid, which smells strongly of jasmine, and boils at 253°-—255°. 
It solidifies in a freezmg mixture to a crystalline mass, which 
becomes liquid again at the ordinary temperature.” 


1 Baeyer and Zincke, Ber. Deutsch. Chem. Ges, xiii. 636. 
2 Beyer, Journ. Prakt. Chem. [2], xxxi. 382. 


46 AROMATIC COMPOUNDS. 





Phenylchloracetic acid, C,H,.CHC1.CO,H, was prepared by 
Radziszewski from mandelic acid by the action of hydrochloric 
acid at 140°} It may be more easily obtained as described 
above, by the action of hydrochloric acid on phenylhydroxy- 
acetonitril. It crystallizes in rhombic plates, melting at 78°. It 
is readily converted into mandelic acid by alkalis and is reduced 
to phenylacetic acid by the action of sodium amalgam on its 
alcoholic solution, or more simply when its ammoniacal solution 
is treated with zinc dust, the reaction being accompanied by a 
considerable evolution of heat (Spiegel). 

Methyl phenylchloracetate, C,§H;.CHCLCO,.CH,, is obtained by 
the action of hydrochloric acid on a solution of the acid in 
methyl alcohol, as an oily liquid, which attacks the eyes violently 
and boils with sight decomposition at 248° 

Phenylbromacetic acid, C,H,;.CHBr.CO,H, is formed when 
mandelic acid is heated sai fuming Rey ioae acid to 
120°—130°,% as well as by the action of bromine at 150° on 
phenylacetic acid (Radziszewski). It separates from carbon 
disulphide in large, monosymmetric crystals, melting at 83°—84°. 

Methylmandelic acid, C,H;.CH(OCH,)CO,H, has been prepared 
by the action of sodium methylate on the methyl ether of 
phenylchloracetic acid. It crystallizes from petroleum-ether in 
small tablets, melting at 71°—72°, and forms salts which crystal- 
lize well (Meyer and Boner). 

Phenylmandelre acid, C,H;.CH(OC,H,)CO,H, is obtained by 
the action of sodium phenate on methyl phenylchloracetate. It 
crystallizes from hot water in fascicular groups of fine needles, 
melting at 108° (Meyer and Boner). 

Mandelie acid chloralide, C,,H,Cl,0;. Mandelic acid, like other 
hydroxy-acids, combines with chloral on heating to form a 


chloralide (Vol. III. Part. II. 147) : 


Pp Yee 
CH, CHC | + COH.COl,= C,H, CHC aa CH.CCl, + 


H,0. 


This compound separates from chloroform in large crystals, 
melts at 82°—83° and boils with slight decomposition at 
305°—310°4 


1 Ber, Deutsch. Chem. Ges. ii. 208. 

2 Meyer and Boner, zbid. xiv. 2391. 

3 Glaser and Radziszewski, Zeitschr. Chem. 1868, 142. 
4 Wallach, Ann. Chem. Pharm. cxciii. 40. 


¥ 


& | 
PHENYLGLYCOCOLL. . 47 





2298 Phenylamido-acetie acid or Phenylglycocoll, C,A,.CH 
(NH,)CO,H, is obtained by heating phenylbromacetic acid with 
ammonia to 100°—110°) and by boiling its nitril with dilute 
sulphuric acid. The latter is formed by the action of alcoholic 
ammonia on phenylhydroxyacetonitril and is a crystalline, 
unstable substance.” 

Phenylamido-acetic acid is only slightly soluble in the ordinary 
solvents; it 1s precipitated from an ammoniacal solution by 
hedrocidor acid in nacreous plates, which melt at 256°, when 
heated in a capillary tube ; when atest tube is employed the acid 
sublimes without fusing, while on rapid distillation 1¢ decomposes 
into carbon dioxide and benzylamine (Vol. III. Part IV. 113). 

It can also be readily obtained from hydrobenzamide (Vol. IIT. 
Part IV. 139), which combines at a low temperature with 
anhydrous hydrocyanic acid : 


JN 
C,H, CH=N O,H,.CH.NH 
\CHC,H, +2HCN = CH.C.HG. 
C.H,.CH=N” OH, CHING 
ON 


The crystalline substance thus formed melts at 55°. When 
it is slightly heated with fuming hydrochloric acid for some 
days, until a clear solution is produced on the addition of water, 
and then boiled for some hours, phenylamido-acetic acid is 
formed. 

Nitrous acid converts the amido-acid into mandelic acid, 
which is also formed from it by the pancreatic fermentation. 
Phenylamido-acetic acid, like other amido-acids, combines with 
both acids and bases. 

Phenylmethylamido-acetic acid or Phenylsarcosin, C,H;.CH 
(NH.CH,)CO,H. When phenylhydroxyacetonitril is allowed to 
stand for some hours at 60°—80° with an alcoholic solution of 
methylamine, the nitril, C,H,;.(CHNH.CH,)CN, is formed and 
yields phenylsarcosin hydrochloride on heating with hydrochloric 
acid. The free phenylsarcosin is liberated from this by ammonia; 
it crystallizes from hot water in fine plates, which sublime when 
heated, without fusing.* 

Phenylhydroxyacetamide, C,H;.CH(OH)CO.NH,. The forma- 


1 Stéckenius, Ber. Dewtsch. Chem. Ges. xi. 2002, 
2 Tiemann, ibid. xiii. 387. 

3 Plochl, ibid. xiii. 2118. 

4 Tiemann and Piest, ibid. xiv. 1982. 


48 AROMATIC COMPOUNDS. 


tion of a crystalline substance by the action of moist chlorine on 
oil of bitter almonds was first observed by Stange, and it was 
mistaken for benzoin (Vol. IIL Part IV. 129) by Robiquet and 
Boutron-Charlard, who obtained it by the same method from 
crude oil of bitter almonds, peach kernels and cherry laurel leaves. 
Winkler, however, found that it differs from this, and was eon- 
firmed by Liebig, who analysed the substance and named it 
“benzoylhydride benzoate,” C,,H,,0O, Laurent then prepared it 
by the action of fuming sulphuric acid on oil of bitter almonds, 
and determined its formula as C,,H,,O,; in conjunction with 
Gerhardt, he subsequently corrected this to C,,H,,O, and named 
the body “ stilbous acid” (acide stilbeux). Gmelin! afterwards 
suggested the formula, C,,H,,O3. 

Zinin was the first to discover that the substance in question 
contains nitrogen and has the formula, C,,H,,NO,, and he also 
found that it is always formed when oil of bitter almonds, which 
still contains hydrocyanic acid, is brought into contact with a 
strong acid. Hydrochloric acid, which was the active agent in 
the production of the body by the action of chlorine, is the most 
convenient acid to employ. A further quantity can be obtained 
by the addition of hydrocyanic acid to the clear liquid from which 
the product has separated. It is scarcely soluble in water, only 
slightly in alcohol, and forms a crystalline powder, or when 
slowly deposited from solution in alcohol or acetic acid, four-sided 
prisms, melting at 195°. On heating with water to 180°, it 
decomposes into benzaldehyde and the amide of mandelic acid.” 
It is, therefore, benzidenephenylhydroxyacetamide, and is formed by 
the combination of benzaldehyde with the nitril of mandelic acid. 
The decomposition by water proceeds according to the following 
equation : 

C,H..CH{( OH) CONG HG, Eo Gis 
C,H;.CH(OH)CO.NH, + CHO.C,H,. 


Phenylhydroxyacetamide is also formed by the action of 
ammonia on the ethyl ether of mandelic acid and by heating 


phenylhydroxyacetimido-ether hydrochloride (Beyer). 


NHC! 
Sap CH (OH)OCS ir C,H,.CH(OH)CO.NH, + C,H,Cl. 


2-5 


1 Handbuch Organ. Chem. iii. 188, where the literature of the subject 
is referred to, 2 Jahresber. Chem. 1868, 624. 


AMYGDALIN. ~ 49 


It crystallizes from hot water in rhombic tablets, melting at, 
132°. 

Phenylhydroxyacetonitril, C,H;CH(OH)CN, is, as already 
mentioned, a constituent of crude oil of bitter almonds. Volkel 
obtained it from this by evaporating the oil with hydrochloric 
acid at a temperature below 100°! and O. Miiller prepared it by 
boiling with alcohol the sodium sulphite compound of benzalde- 
hyde together with potassium cyanide? It is also readily formed 
when benzaldehyde is heated with 20 per cent. hydrocyanic 
acid,® or still more simply by acting upon it with the nascent acid. 

It is an oily liquid, which is insoluble in water, but readily 
soluble in alcohol and ether, solidifies at —10° and decomposes 
at 170° into hydrocyanic acid and benzaldehyde. It yields 
styrolylamine on reduction (p. 7). 

Phenylhydroxyethenylamidoxime, C,H,.CH(OH)C(NOH)NH.,, 
is formed by the combination of the nitril with hydroxylamine, 
and forms crystals. which melt at 158°—159°4 


AMYGDALIN OR GLUCOPHENYLHYDROXYACETONITRIL, 
C,,H,,NO,, + 3H,0. 


2299 The history of this compound, the first known gluc- 
oside, has already been given under benzaldehyde. It occurs 
in the seeds of the Amygdalaceae, Drupaceae, and Pomaceae ; 
bitter almonds contain 2°8—4 per cent., peach kernels 2°35 per 
cent., cherry kernels 0°82 per cent., plum kernels 0°96 per cent., 
and apple pips 0°6 per cent. It also occurs in other parts of 
these plants, and has been found in the leaves of the cherry 
laurel (Cerasus Lawrocerasus), in the bark, flowers, and leaves 
of the bird-cherry (Prunus Padus), m the young shoots of 
apple and plum trees, in the buds and bark of the mountain 
ash (Sorbus Aucuparia), of the hawthorn, &c. All these 
portions of the plants yields oil of bitter almonds containing 
hydrocyanic acid on distillation with water. It has not yet 
been decided whether the hydrocyanic acid which has been 
obtained from other plants is also derived from amygdalin. The 
shrubby members of the Spirea family (Spirwa aruncus, Spirea 
sorbifolia, and Spirea japonica) yield a distillate which contains 

1 Ann, Chem. Pharm. lii. 361. 
2 Ber. Deutsch. Chem, Ges. iv. 980. 


3 Tiemann and Friedlinder, <bid. xiv. 1967. 
4 Gross, ibid. xviii. 1074 and 2477. 


50 AROMATIC COMPOUNDS. 


hydrocyanic acid, while salicylaldehyde is found in that given 
by some of the herbaceous plants of the same group.! Henry 
and Boutron-Charland found 0°04 per cent. of hydrocyanic acid 
in the sap of the bitter cassava (Manihot utilissima), which is the 
source from which arrow-root is prepared, and which is known 
to be poisonous.” It has also been detected in Chardinia xeran- 
themoides, one of the Compositae which occurs in Asia Minor | 
and Persia, in the fruit of Ximenia americana, which is an 
article of food in the tropics, and in Lpomoea dissecta, which 
is indigenous in Trinidad,® as well as in Agaricus oreades,s 
while the seeds of the vetch (Vicia sativa), which contain 
no amygdalin, yield both benzaldehyde and hydrocyanic acid, 
benzaldehyde being also found in the germinating seeds of 
cress (Lepidium sativum).® 

In order to prepare amygdalin, bitter almonds are freed as far 
as possible from fatty oil by pressing, and the mass repeatedly 
extracted with boiling alcohol; the alcohol is then distilled off, 
and the residue recrystallized from boiling alcohol. 

It crystallizes in lustrous plates or scales, or from water in 
transparent, rhombic prisms, which become anhydrous at 120°, 
and then melt at 200°, soldifying to an amorphous mass on 
cooling. At 8°-12° it dissolves in twelve parts of water, while it 
is soluble in every proportion in boiling water. It is slightly 
soluble in cold, more readily in boiling alcohol and insoluble 
in ether. Its solution is levorotatory. On the addition 
of emulsin to its aqueous solution, it decomposes into grape 
sugar and phenylhydroxyacetonitril, which is partially decom- 
posed by distillation into benzaldehyde and hydrocyanic acid. 
The same decomposition takes place on boiling with dilute 
hydrochloric acid. 

When it is treated with zinc and hydrochloric acid, styrolyl- 
amine is formed,’ while cyanogen chloride and_ benzidene 
chloride are obtained by the action of phosphorus penta- 
chloride. § 

It has a sweet taste, followed by a bitter after-taste. Accord- 
ing to Frerichs and Wohler it is not poisonous; symptoms of 

1 Wicke, Ann. Chem. Pharm. 1xxxiii. 175. 
2 Ibid. xviii. 172. 

3 Flickiger and Hanbury, Pharmacographia, II. ed. 250. 

4 v. Losecke, Jahresber. Chem. 1871, 812. 

® Ritthausen and Kreusler, Jowrn. Prakt, Chem. [2] ii. 333. 

6 Schulze, zbid. Ixxxvii. 129. 


7 Fileti, Ber. Deutsch. Chem. Ges, xii. 297. 
8 Schiff, Ann. Chem. Pharm. cliv. 337. 


CONSTITUTION OF AMYGDALIN. 5} 





poisoning were only observed in two cases, in which doses of 
two and five grams, respectively had been administered to dogs, 
and they then resembled those of prussic acid poisoning, with 
the difference that they prevailed for six to eight hours without 
alteration, after which the stupor gradually passed away and 
the animals soon recovered. The breath of both these animals 
smelt of hydrocyanic acid, and the same smell was noticeable 
in the urine after the addition of almond emulsin.! According 
to Moriggia and. Ossi, amygdalin exerts a poisonous action even 
in the absence of emulsin, especially in the case of the 
graminivora.? 

Heptacetylamygdalin, CH. )(C,H;0),NO,,, was prepared by 
Schiff by boiling amyg gdalin with acetic anhydride. It crystal- 
lizes from aléohol in long, silky needles, which are insoluble in 
water. 

Amygdalic acid or Glucomandelre acid, C,,H,,0,3, was obtained 
by Liebig and Wohler from amygdalin by boiling it with 
baryta water : 


CopHy,NO, + 2H,0 = C,,H,0,, + NH. 


It is a white, crystalline, very deliquescent mass (Schiff), 
which forms amorphous salts. 

The following formule explain the constitution of amygdalin and 
amyedalic Neen (Schiff), which are the derivatives of a diglucose : 


Amygdalin. Amygdalic acid. 
C.H.O(OH), C,H,0(OH), 
O<CH {0(OH),OCH<6 Fy stolen ,0(0H),OCH<¢, yf" By 


AROMATIC SUBSTITUTION PRODUCTS OF 
MANDELIC ACID. 


2300 Metanitromandelic acid, C,H,(NO,)CH(OH)CO,H. The 
nitril of this acid is formed by the action of nascent hydro- 
cyanic acid on metanitrobenzaldehyde. It is a viscid liquid, 
which is converted by the action of hydrochloric acid on its 
solution in a mixture of ether and alcohol into the hydro- 
chloride of nitrophenylimido-ether, C,H,(NO,)CH(OH)C(NH)O 


1 Frerichs and Wohler, zbid. xv. 337, 
2 Ber, Deutsch. Chem. Ges. ix. 198. 


52 AROMATIC COMPOUNDS. 


C,H,.HCl, which crystallizes in needles and is decomposed by 
water with formation of the ether of nitromandelic acid. This is 
readily soluble in dilute caustic soda; when this solution is 
acidified with hydrochloric acid and extracted with ether, the 
ethereal solution contains free nitromandelic acid, which remains 
on the evaporation of the ether. It has a strongly acid and 
intensely bitter taste, is slightly soluble in water, alcohol and 
ether, and separates from the last on addition of petroleum- 
spirit im small, yellowish, vitreous rhombohedra, melting at 
119°=120°. 

Ethyl metanitrophenylthydroayacetate, C,H,(NO,)CH(OH)CO,. 
C,H;, crystallizes from hot petroleum-spirit in silky needles, 
melting at 63°.1 

Metanitrophenylamido-acetie acid, C,H,(NO,)CH(NH,)CO,H,: 
is formed by the action of nitric acid on a solution of amido- 
mandelic acid in concentrated sulphuric acid. It is readily 
soluble in hot water and is precipitated by alcohol in fine, 
pointed, silky needles, which melt with decomposition at 172°. It 
is converted into metanitromandelic acid by the diazo-reaction. 

Metamidophenylamido-acetic acid, C,H,(NH,)CH(NH,)CO,H, 
is obtained by the action of tin and hydrochloric acid on the 
preceding compound. It is precipitated by alcohol from its hot 
aqueous solution in the form of flat, microscopic needles, which 
melt with decomposition at 214°. Like the preceding com- 
pounds it forms salts with both acids and bases.” 

Dioxindol, C,H,NO,, is the anhydride of orthamidomandelic 
acid, which is not known in the free state. It was obtained by 
Knop by the reduction of isatin, which he called hydridinic 
acid. and was then investigated by him and Baeyer.t In order 
to prepare it, a solution of isatin is treated with a little hydro- 
chloric acid and boiled up with zinc dust, the dioxindol bemg 
extracted with ether.® It dissolves in twelve parts of cold, 
and six parts of boiling water from which it crystallizes in 
groups of needles or in transparent, yellow, rhombic prisms, 
while it is soluble in fifteen parts of cold, and ten of hot 
absolute alcohol, and crystallizes from this solvent in dazzling 
white, transparent crystals. It melts at 180° to a violet liquid 
and decomposes when more strongly heated with formation of 

1 Beyer, Journ. Prakt. Chem. [2] xxxi. 382. 
2 Plochl and Loé, Ber. Deutsch. Chem. Ges. xviii. 1179. 
3 Journ. Prakt. Chem. xevii. 65. 


4 Ann. Chem. Pharm. exl. 1. 
5 Baeyer, Ber. Deutsch. Chem. Ges. xii. 1309. 


SALTS OF DIOXINDOL. 53 


aniline. Ammonia colours its alcoholic solution violet, and 
produces a precipitate of the same colour on boiling, which is 
soluble in hydrochloric acid. The aqueous solution of dioxindol 
absorbs oxygen from the air with formation of isatin and 
isatyde, C,,H,,N,O,. Phosphorus pentachloride converts it into 
chloroxindol chloride (p. 23) :1 


CH(OH) 
“G me 
i aD, 
OHG. 
CH See + 2POCI, + 2HCL. 


CO + 2PCl, = 


Dioxindol hydrochloride, C,H,NO,HCl, forms warty crusts, 
readily soluble in water. 

Dioxindol sulphate, C,H,NO,.H,SO,+ H,O, is obtained by 
dissolving dioxindol in sulphuric acid; water precipitates it 
in white flakes, which dry to a radiating crystalline mass. 

Sodium dioxindol, C,H,NO,Na+2H,O, is formed by the 
action of sodium amalgam and water on isatin; it separates in 
small cubes, which are slightly soluble in water, less readily in 
caustic soda solution and are precipitated by a mixture of 
alcohol and ether in silver-lustrous scales. 

Barium dioxindol, (C,H,NO,) Ba + 4H,O, is formed by the 
addition of barium chloride to the solution of sodium dioxindol, 
as a crystalline precipitate, which separates from a dilute 
solution in small cubes, 

These compounds are probably salts of orthamidomandelic 
acid, which immediately decomposes into water and dioxindol 
when liberated by acids : 


AY OH)UO,OF i Garis 
O;A i OM a CO + H,0. 
\NH, \_NH-* 

Silver dioxindol, CSH,NO,Ag, is obtained as a white crystal- 
line precipitate, when ammonia is added to a solution of sodium 
oxindol and silver nitrate. It is an unstable substance, which 
decomposes in the moist state with formation of benzaldehyde 
and metallic silver, and probably has the following constitution : 
/CHOH) 

OH p00 


1 Ber. Deutsch. ee Ges, xii, 458. 


54 AROMATIC COMPOUNDS. 





2301 Acctyldiovindol, Cs,H,N(CO.CH,)O,, is obtained by 
heating dioxindol to 140° with acetic anhydride ; it crystallizes 
from hot water in short prisms, melting at 127°4 

Acetylorthamidomandelie acid or Acetylhydridinic acid 
C,H,(NH.CO.CH,)(CH.OH)CO,H, is formed when the preceding 


compound is dissolved in baryta water : 


CH.OH // CH(OH)CO.OH, 
CHingmpeOh ie 33 31.0) = CHK 
\N.C0.C NH.CO.CH, 


It is also obtained when an acetic acid solution of acetyl- 
isatic acid, C,H,(NH.CO.CH,)CO.CO,H, is treated with sodium 
amalgam.? It crystallizes in needles, which are readily soluble 
in water and alcohol, melt at 142°, and on further reduction by 
means of sodium amalgam or hydriodic acid and phosphorus, 
are resolved into acetic acid and oxindol. 

Nitrosodiowindol, C,5H,N(NO)O,, is prepared by the action of 
nitrous acid on an alcoholic solution of dioxindol, and crystallizes 
from hot water in yellow, moss-like groups of needles, which 
are very brittle, melt at 300°—310° and sublime at 340° in white 
needles. 

Ammonium nitrosodioxindol, 2 C,H,(NH,)(NO)NO, + H,0, 
crystallizes in silky plates, which are only very slightly soluble 
in water. 

Barium nitrosodioxindol, C,H,Ba(NO)NO,, is thrown down 
as a crystalline precipitate, when barium chloride is added to 
an aqueous solution of nitrosodioxindol ; it is soluble in boiling 
water. 

Silver nitrosodioxindol, C,H, Ag,(NO)NO,, is obtained by the 
addition of silver nitrate to the solution of the ammonium salt, 
in the form of a yellowish white precipitate. 

Nitrosodiexindol contains two hydrogen atoms which can n be 
replaced by metals and appears to be an isonitroso-compound, 


its constitution being expressed by one of the following 
formule : 


JE. OH JPN On 
C,H, K2 00 CHK >0.0H 
| aie 
OH 


1 Suida, Ber. Deutsch. Chem, Ges. xii. 1826. 2 Ibid. xi. 586. 


/ 


SUBSTITUTION DERIVATIVES OF DIOXINDOL. 55 





Azodioxindol, C,H,N,O,, 1s formed when nitrosodioxindol is 
boiled with dilute caustic potash solution and ferrous sulphate, 
and crystallizes in lustrous, white, prismatic needles, which are 
shightly soluble in water, readily in caustic potash and boiling 
alcohol, sublime at 260° in lustrous, quadratic tablets and melt 
at 300°. Silver azodioxindol, C,H,Ag,N,O,, is obtained as 
a white, crystalline precipitate by the addition of silver nitrate 
and then ammonia to a solution of this body. 

Azoxindol, 2C,H,N,O + H,O,isobtained when nitrosodioxindol 
is treated with a little water and sodium amalgam; it crystallizes 
from alcohol in cubes, which become anhydrous at 140° and 
sublime at 220° in plates, without previously melting. It 
contains one hydrogen atom which can be replaced by metals. 

Substitution products of dioxindol have been prepared by 
Baeyer and Knop by the action of chlorine or bromine on its 
aqueous solution : 


Chlorodioxindol, C,H,CINO,, yellowish needles. 
Dichlorodioxindol, C,H,Cl,NO., dirty green scales. 
Bromodioxindol, C,H, BrNO,, light yellow needles. 
Dibromdioxindol, C,H, Br,NO,, dark red needles. 


2302 Orthohydroxymandelic acid, C,H,(OH)CH(OH)CO,H, 
was prepared by Pléschl, who named it salicylglycolic acid, by 
combining salicylaldehyde with hydrocyanic acid and decom- 
posing the product with hydrochloric acid. It is also formed 
by the action of water and sodium amalgam on hydroxybenzoyl- 
formic acid,! and has hitherto only been obtained in the form of 
a syrup; it forms salts which are crystalline.” 

Methylparahydroxymandelic acid, C,H ,(OCH;,)CH(OH)CO,H 
The nitril of this acid is formed when anisaldehyde is heated 
with aqueous hydrocyanic acid, and is a crystalline substance, 
melting at 63°. The acid is obtained from it by heating with 
alcohol and hydrochloric acid ; it crystallizes in ice-like masses, 
in which small needles can be distinguished, and melts at 93°. 


O 
Methylenedihydroxymandelic acid, CH C,H, CH(OH) 
O 


CO,H. The nitril is formed by heating piperonal (Pt. IV. p. 347) 
with hydrocyanic acid. ‘The acid, which is prepared from this 


1 Baeyer and Fritsch, Ber. Deutsch. Chem. Ges, xvii. 973. 
* Ibid. xiv. 1317. 
3 Tiemann and Kohler, zbid. xiv. 1976. 


270 


56 AROMATIC COMPOUNDS. 


by the usual method, forms granular crystals, melting at 152° 
153°; it readily decomposes carbonates, but is very unstable 
and forms a resinous mass even when the aqueous solution is 


boiled. 


BENZOYLMETHYL COMPOUNDS. 
METHYLPHENYLKETONE, CH.CO.C,H,. 


2303 This compound, which is usually known as acetophenone 
‘and is the simplest aromatic ketone, was first prepared by 
Friedel by the distillation of a mixture of calcium acetate and 
benzoate,” while Popow obtained it by the action of zinc methyl 
on benzoyl chloride.* It is also readily formed when a mixture 
of acetyl chloride and benzene is heated with aluminium 
chloride,t and, together with benzoic acid, when ethylbenzene 
is oxidized by a solution of chromium trioxide in glacial acetic 
acid.° In addition to these methods it may be obtained by 
agitating phenylacetylene with 75 per cent. sulphuric acid : ® 


C.H,.C=CH + H,O = C,H,.CO.CH,. 


When sodium aceto-acetic ether is acted upon by benzoyl 
chloride, benzoylaceto-acetic ether, CH;.CO.CH(CO.C,H,)CO,,. 
C,H,, is formed, and decomposes on heating with water or 
alkalis into acetic acid, acetophenone, carbon dioxide and 
alcohol.’ Acetophenone crystallizes in large plates, which melt 
at 20°5°;*% it boils at 202°,° and has an aromatic odour resembling 
that of oil of bitter almonds. It is oxidized by chromic acid 
solution to benzoic acid (Popow) and is reduced by nascent 
hydrogen to methylphenyl carbinol; the pinacone, C,,H,,0,, 
which will be subsequently Eecatest is also formed in shis 
reaction. 

Its action upon the organism is similar to that of chloral, 
since doses of 0°05—0°15 grm. produce quiet sleep; Dujardin- 


1 Lorenz, Ber. Deutsch. Chem. Ges. xiv. 794. 

2 Compt. Rend. xlv. 10138. 

3 Ber. Deutsch. Chem, Ges. iv. 720. 

4 Friedel and Crafts, Ann. Chim. Phys. [6] i. 507. 

5 Friedel and Balsohn, Bull. Soc. Chim. xxxii. 616. 

6 Ibid. xxxv. 55. 

7 Bonné, Ann. Chem. Pharm. elxxxvii. 1. - - 

8 Stadel and Kleinschmidt, Ber. Deutsch. Clee Ges. xiii. 836. 
9 Fittig and Wurster, Ann. Chem. Pharm. excy. 160. 


SUBSTITUTION DERIVATIVES OF ACETOPHENONE. 57 


Beaumetz and Bardet have therefore called it hypnone! It is 
converted in the system into hippuric acid, which is excreted 
with the urine. After long-continued use, however, a portion is 
excreted through the lungs and imparts its characteristic smell 
to the breath. 
CH, NX 

C—N.OH, crystallizes from 
. CH” 
hot water in silky needles, which melt at 59° and are extremely 
soluble in alcohol, ether, acetone, etc.” 


Acetophenone-acetoxime, 


CH, 

Acetophenonephenylhydrazine, No —N,H.C,H,, crystal- 

CoH, 
lizes from hot alcohol in fine, white needles, melting at 105°.8 

Parachloracetophenone, C,H,CLCO.CH,, is obtained by heating 
chlorobenzene with acetyl chloride and aluminium chloride. It 
forms crystals, melting at 20°, boils at 230°—231°, smells like 
acetophenone, but somewhat sharper, and is oxidized by 
potassium permanganate to parachlorobenzoic acid.* 

Para-iodo-acetophenone or Acetyliodobenzene, C,H,I.CO.CH,, 
was prepared by Klinger from the amido-compound by the 
diazo-reaction. It crystallizes from ether in small plates or 
flat needles, melting at 79°, and yields para-iodobenzoic acid on 
oxidation. 

Orthonitro-acetophenone, CH,.CO.C,H,.NO.,, is formed, together 
with the meta-compound, by the nitration of acetophenone.’ It 
may be obtained pure by acting upon sodiumaceto-acetic ether 
with orthonitrobenzoyl chloride and decomposing the ethyl 
benzoylaceto-acetate by boiling with dilute sulphuric acid.® It 
is a yellowish oil, which is volatile with steam and is oxidized 
to orthonitrobenzoic acid by potassium permanganate (Engler). 

Metanitro-acetophenone has been prepared from metanitro- 
benzoyl chloride (Gevekoht) ; it is, however, more easily obtained 
by the nitration of the ketone, which yields this derivative alone 
when the mixture is well cooled.” It is volatile with steam and 
forms colourless needles, which melt at 81° and are converted by 
oxidation into metanitrobenzoic acid. 

1 Compt. Rend. ci. 960 and 1506 ; Bull. Therap. Jan. 15, 1886. 
2 Janny, Ber. Deutsch. Chem. Ges. xv. 2781. 

3 Reisenegger, Ber, Deutsch. Chem. Ges. xvi. 662. 

4 Gautier, Bull. Soc. Chim. xliii. 602. 

5 Emmerling and Engler, zbid. iii. 886 ; Engler, bid. xviii, 2238. 


6 Gevekoht, Ann. Chem. Pharm. ccxxi. 323. 
7’ Buchka, Ber. Dewtsch. Chem. Ges. x. 1714. 


58 AROMATIC COMPOUNDS. 





Paranitro-acetophenone was obtained by Drewsen by boiling 
paranitrophenylpropiolic acid, C,H,(NO,)C =C.CO,H, with 
sulphuric acid of 75 per cent.; this acid decomposes into carbon 
dioxide and paranitrophenylacetylene, which then combines with 
water to form the ketone.1 Gevekoht subsequently prepared it 
from paranitrobenzoyl chloride. It crystallizes from hot water 
in yellowish prisms, melting at 80°—81°. 

Orthamido-acetophenone, CH,,.CO.C,H,.NH,, is formed by the 
reduction of the nitro-compound with tin and hydrochloric acid, 
as well as by the action of sulphuric acid of 75 per cent. on 
amidophenylacetylene,? C,H,(NH,)C = CH. It is a yellowish 
oil, which can be volatilized without decomposition, and yields 
a vapour with a penetrating odour, which adheres to the skin 
for a long time, while, when diluted with air, the odour loses 
its pungent character and becomes more agreeable. It forms 
salts with acids, and on boiling with acetic anhydride yields 
acetorthamido-acetophenone, CH,.CO.C,H,.NH(CO.CH,), which 
crystallizes from petroleum-spirit in silky needles, melting at 
76°—77°. The corresponding benzoyl derivative, benzoylortho- 
amido-acetophenone, CH,.CO.C,H,.NH(CO.C,H,), is formed by 
the action of benzoyl chloride; it crystallizes in large, yellowish 
prisms, and melts at 79°—80°. As a secondary base it forms a 
nitroso-compound, which crystallizes in long, colourless needles, 
melting at 54°—55°, and is decomposed on heating with sulphuric 
acid with formation of indigo.* 

Lthylorthamido-acetophenone, CH,.CO.C,H,.NH(C,H,), is 
obtained by heating the amidoketone with ethyl bromide, as 
.a yellowish oil, which possesses a very characteristic odour, quite 
distinct from that of the amido-acetophenone (Baeyer). 

Metamido-acetophenone is formed by the action of tin,‘ or 
zinc,’ and hydrochloric acid on the corresponding nitro-compound. 
It is soluble in alcohol and crystallizes in» small, yellow 
pyramids, melting at 92°—93°. Its hydrochloride is partially 
decomposed by water. 

Paramido-acetophenone was obtained by Drewsen by the re- 
duction of the nitro-derivative, and Klinger, who named it 
acetylaniline, found that it is also formed when two parts of 
aniline, three parts of zinc chloride, and five parts of acetic 

1 Ann. Chem. Pharm. cexii. 159. 
2 Baeyer and Blom, Ber. Deutsch. Chem. Ges. xv. 2153 ; xvii. 963. 
3 Baeyer, ibid. xvii. 970. 


4 Buchka, Joc. cit. ; Engler, Ber. Deutseh, Chem. Ges. xi. 982. 
®* Hunnius, ibid. x. 2009. 


PARAHYDROXY ACETOPHENONE. 59 





anhydride are heated to the boiling-point for four to five hours.’ 
It crystallizes from hot water in fan-shaped groups of long, flat 
needles, melting at 105°—106°, boils at 293°—295° without 
decomposition, and combines with acids to form salts which 
crystallize well. When heated with acetic anhydride it yields 
acetorthamido-acetophenone, which crystallizes from hot water in 
small needles, melting at 166°—167°. 

Dimethylparamido-acetophenone, CH,.CO.C,H,.N(CH,),, is 
formed when paramido-acetophenone is heated with methyl 
iodide, and crystallizes from hot water in yellowish plates, melt- 
ing at 58°—59°. 

Acetophenonesulphonic acid, CH,.CO.C,H,.SO,H, is formed 
when acetophenone is heated for some time with concentrated 
sulphuric acid. The free sulphonic acid, which is prepared by 
the decomposition of its lead salt with sulphuretted hydrogen, 
is very hygroscopic and forms a compound of the following con- 
stitution with phenylhydrazine : 


This crystallizes in nacreous plates and is resolved into 
phenylhydrazine and barium acetophenonesulphonate by boiling 
with baryta water.? 

2304 Parahydroxyacetophenone, CH,.CO.C,H,OH, which is 
also called acetylphenol, was prepared by Klinger by means of 
the diazo-reaction, while Michael and Palmer obtained it by 
heating phenol with glacial acetic acid and zinc chloride: 


CH,.CO.OH + C,H,.0H = CH,.CO.C,H,.OH + H,0. 


It crystallizes from alcohol in long prismatic needles or short 
prisms, which are insoluble in water but dissolve in hot hydro- 
chloric acid and melt at 108°. 

Paradihydroxyacetophenone, CH;.CO.C,H,(OH),, or Quinaceto- 
phenone, is formed when two parts of quinol are heated to 140°— 
150° with three parts of glacial acetic acid and three parts of zinc 
chloride. It is readily soluble in alcohol and ether, crystallizes 


1 Hunnius, Ber. Deutsch. Chem. Ges. xviii. 2687. 
2 Krekeler, zbid. xix. 2623. 
3 Amer. Chem. Journ. vii. 277. 


60 AROMATIC COMPOUNDS. 


from hot water in yellowish green, dendritic forms, resembling 
those of sal-ammoniac, and melts at 202°. Its aqueous solution 
is coloured a fugitive deep blue by ferric chloride ; it dissolves in 
alkalis with formation of a light yellow solution, which soon 
becomes brown in the air. Like quinol it reduces Fehling’s 
solution. 

Metadthydroxyacetophenone or Resacetophenone is prepared from 
resorcinol in a similar manner to the preceding compound, and 
crystallizes from hot dilute hydrochloric acid in colourless 
rhombic plates or needles, melting at 142°. The dilute aqueous 
solution is coloured wine-red by ferric chloride. On heating 
with acetic anhydride, the monacetate, CH,.CO.C,H,(OH) 
O.C,H,O, is formed, which crystallizes from alcohol in fine 
needles, melts at 72° and boils at 303°. All attempts to prepare 
the diacetate have proved unsuccessful. 

Methylresacetophenone or Paeonol, C,H,(0H)(OCH,)CO.CH,, 
occurs to the extent of 3—4 per cent. in the aromatic root of 
Paconia mutan from Japan, and volatilizes on distillation with 
steam in fine needles, melting at 47°. 

Nitroresacetophenone, CH,.CO.C,H,(NO,)(OH),, is formed by 
the action of ordinary nitric acid on the ketone and crystallizes 
from dilute alcohol in long, yellowish needles, melting at 142°.8 

It is reduced to amidoresacetophenone, CH,.CO.C,H,(NH,) 
(OH),, by tin and hydrochloric acid; the hydrochloride of this 
substance crystallizes in lustrous prisms.* 

Trihydroxyacetophenone or Gallacetophenone, CH,.CO.C,H,(OH)s, 
has been prepared by Nencki and Sieber from pyrogallol and 
acetic acid, and crystallizes from hot water in nacreous plates, 
melting at 168°. Its alkaline solution becomes coloured yellow 
and then brown in the air. 

When these compounds are heated with zine chloride and 
acetic acid, colouring matters which will be subsequently de- 
scribed are formed. 

1 Nencki and Schmid, Journ. Prakt. Chem. [2] xxiii. 556. 
2 W. Will. Ber. Deutsch. Chem. Ges. xix. 1776. 


3 Nencki and Sieber, Jowrn. Prakt. Chem. [2] xxiii. 147. 
4 Ibid, [8] xxiii. 537. 


BENZOYLMETHYL ALCOHOL. 61 





BENZOYLMETHYL ALCOHOL. 
C,H,CO.CH,.OH. 


2305 This compound was first prepared by Graebe from the 
chloride and named acetylbenzol alcohol. Hunaeus and Zincke 
then obtained benzoylcarbinol by the oxidation of styrolene 
alcohol with nitric acid,? and Hunnius, who named it aceto- 
phenone alcohol, prepared it from its bromide.® 

Benzoylmethyl alcohol crystallizes from alcohol or ether in 
large, lustrous, six-sided tablets, which apparently belong to the 
monosymmetric system, and from petroleum-spirit in prisms or 
thick plates, melting at 85°5°—86°. It separates from water or 
dilute alcohol in large, lustrous, hydrated plates, which probably 
have the formula C,H,C(OH),CH,.OH, melt at 73°—74° and 
on careful heating lose water, but are very liable to decompose 
with formation of benzaldehyde and a very volatile substance 
having a penetrating odour, which is probably formaldehyde. 

As a ketone, benzoylmethyl alcohol combines with the acid 
sulphites of the alkalis, reduces ammoniacal silver solution and 
Fehling’s solution, mandelic acid being the chief product, accom- 
panied by benzaldehyde, benzoic acid and benzoylformic acid.* The 
reduction probably proceeds according to the following equation: 


Chea C,H, 
| 

C(OH), + 0 = CH(OH) + H,O 

| 

CH,.OH CO.OH 


Benzoylmethyl chloride, was prepared by Graebe by the action of 
chlorine on boiling acetophenone and was named by him chloro- 
acetylbenzol. It was then investigated by Stidel.® It is readily 
soluble in alcohol, ether, &c., and crystallizes in thick, rhombic 
tablets, which melt at 58°—59° and have an agreeable aromatic 
odour. It boils at 244°—245° and yields a vapour which produces 
a flow of tears. 

Benzoylmethyl bromide, C,H;.CO.CH,Br, was obtained by 


1 Ber. Deutsch. Chem. Ges. iv. 34. 

2 Ibid. x. 1486 ; Zincke, Ann. Chem. Pharm. ccxvi. 306. 
3 Ber. Deutsch. Chem. Ges. x. 2006. 

4 Breuer and Zincke, ibid. xiii. 635. 

5 Ibid. x. 1830. 


62 AROMATIC COMPOUNDS. 





Emmerling and Engler, who named it bromacetophenone, by the 
direct action of bromine on acetophenone.! In order to prepare 
it, one molecule of bromine is gradually added to a molecule of 
acetophenone dissolved in carbon disulphide (Hunnius), a current 
of dry carbon dioxide being simultaneously passed through the 
liquid to remove the hydrobromic acid and carbon disulphide 
(Stiidel and Kleinschmidt). It crystallizes from dilute alcohol 
in rhombic prisms and from ether in tablets, which are apparently 
isomorphous with those of the chloride,? and melt at 50°. Its 
vapour attacks the eyes violently. 

Orthonitrobenzoylmethyl bromide, OC,H,(NO,)CO.CH,Br, is 
formed when equal molecules of bromine and_ orthonitro- 
acetophenone are brought together in glacial acetic acid 
solution. It crystallizes from petroleum-spirit in fine, con- 
centrically-grouped needles, which melt at 55°—56°, have a 
bitter taste and an exceptionally violent action on the eyes.’ 

Benzoylmethyl acetate, C,H,.CO.CH,.0.C,H,0, is formed by 
heating the chloride (Graebe), or bromide (Hunnius) with alcohol 
and potassium acetate, or the alcohol with acetic anhydride 
(Hunaeus and Zincke). It is readily soluble in alcohol, ether, 
and petroleum-spirit, from which it crystallizes in lustrous, 
rhombic tablets, melting at 49°—49°5°. 

Benzoylmethyl benzoate, C,H;.CO.CH,.0.C,H,O, crystallizes 
from hot alcohol in small tablets, which are frequently massed 
together in the form of flat needles, and melt at 117°—117°5°. 

Benzoylmethyl phenyl ether, C,H;.CO.CH,.0.C,H,, is obtained 
by boiling the bromide with an alkaline solution of phenol. It 
crystallizes from alcohol in prisms, melting at 72°, and is not 
decomposed by caustic soda solution. On fusion with caustic 
potash, however, it decomposes into phenol and acetophenone, 
which is then partially oxidized to benzoic acid.* 


1 Ber. Deutsch. Chem. Ges. iv. 148. 

* Stadel, bid. xvi. 22. This chemist has proposed the name of phenacyl for 
the radical benzoylmethyl. 

3 Gevekoth, Ann. Chem. Pharm. ccexxi. 323. 

* Mohlau, Ber. Deutsch. Chem. Ges. xv. 2497. 


ISO-INDOL. 63 


BENZOYLMETHYLENE-COMPOUNDS. 


2306 These are formed by the replacement of two hydrogen 
atoms in the methyl group of acetophenone. 

Benzoylmethylene chloride, C,H,;.CO.CHCI,, is formed when 
aluminium chloride is gradually added to a boiling mixture of 
benzene and dichloracetaldehyde, and is a liquid which smells 
like pepper, has a biting taste and boils at 24'7°—248° with 
slight decomposition.! 

Benzoylmethylene bromide, C,H;.CO.CHBr,. This compound, 
which is usually called dibromacetophenone, is best obtained by 
gradually adding the calculated quantity of bromine to aceto- 
phenone dissolved in glacial acetic acid, then heating to 65°-70° 
and pouring the solution into cold water. The product is purified 
by recrystallization from petroleum-spirit.*, It forms rhombic 
tablets (Fittig and Wurster) which melt at 36°-37°. Potassium 
permanganate oxidizes it to benzoic acid (Hunnius), while 
ammonia decomposes one portion into benzamide and methylene 
bromide, while the remainder is converted into 7so-indileucin 
C,,H,.N,0, which will be subsequently described. 

Orthonitrobenzoylmethylene bromide, C,H,(NO,).CO.CHBr,, 
was prepared by Gevekoth by the bromination of orthonitro-aceto- 
phenone. It crystallizes from petroleum-ether in small prisms, 
melting at 85°-86°, has a bitter taste, causes a copious flow of 
tears and, like orthonitrobenzoylmethyl bromide, is converted 
into indigo by the action of alcoholic ammonium sulphide. 

Metanitrobenzoylmethylene bromide is formed by the nitration of 
the dibromide and by the bromination of metanitrobenzoylmethyl 
bromide. It crystallizes from alcohol in yellowish tablets, melt- 
ing at 59° (Engler and Hassenkamp). 

2307 Iso-indol, C,,H,,N,, is obtained by boiling benzoylmethyl 
chloride with aqueous ammonia? or the acetate with alcoholic 
ammonia. It is, however, best prepared by allowing the bromide 
to stand in contact with the latter reagent in the cold: 4 


2C,H,CO.CH,Br + 2NH, = C,,H,,N, + 2H,0 + 2HBr. 


1 Gautier, Compt. Rend. cii. 812. 

2 Engler and Hassenkamp, ibid. xviii. 2240. 

8 Staidel and Riigheimer, Ber. Deutsch. Chem. Ges, ix. 563; Stiidel, zbid. x. 
Stadel and Kleinschmidt, <bid. xi. 1744. 

4 Ibid. xiii. 836. 


64 AROMATIC COMPOUNDS. 








It is only slightly soluble in the usual solvents, and crystallizes 
from hot alcohol or glacial acetic acid in small plates, needles or 
prisms, which are pleochroitic and show all possible colours, 
from the deepest red, green, yellowish green, yellow to indigo- 
blue; larger crystals a al by transmitted light often show this 
eric | series of colours when they are rotated about their axes. 
It melts at 194°-195°, dissolves in hot concentrated hydrochloric 
acid and is reprecipitated by the addition of water. It sublimes 
when fused with potash or heated with lime, and is not attacked 
by heating with ethyl iodide, acetyl chloride or acetic anhydride ; 
hydriodic acid, however, converts it into a base melting at 
26). 

The name of iso-indol was given to this substance because it 
was believed to be isomeric with indol, C,H,N, (p. 36), until 
V. Meyer and Treadwell found that its formula must be doubled, 
since its vapour density is 7:91-7:99. 

Phenylisoindol, C,,H,.(C,H;),N,, is formed by boiling benzoyl- 
methyl bromide with an excess of aniline. It is readily soluble 
in the usual solvents, and crystallizes from carbon disulphide in 
lustrous plates, which melt at 181° and sublime readily. It is 
also not attacked by fused caustic soda or heated lime. Its 
vapour density is 18°33, and it should therefore be called 
diphenyldt-iso-indol® 


THE INDAZOL GROUP. 


merit abet mgt 


—oH 
We: C,H, KiNG 


aN 
he HX > a 2: 


on | > 


2308 Indazol, which contains seven carbon atoms, is described 
here along with its homologues, since these bodies are obtained 
by simple reactions from orthamido-acetophenone. E. Fischer, 
who has investigated these compounds in conjunction with 
Kuzel * and Tafel, names the two last methylindazol and methyl- 
isindazol. In order to distinguish the derivatives which are 


1 Ber. Deutsch. Chem. Ges. xvi. 342. 
2 Mohlau, zbid. xiv. 173 ; xv. 2480. 
3 Ann. Chem. Pharm. cexxi. 261. 

4 Ibid. ecxxvii. 303. 


INDAZOL. i 65 





formed by replacing the imido-hydrogen by alcohol radicals, he 
designates the “ five-atom nitrogen ring”: 


with the symbol Iz, and numbers the positions in rotation, com- 
mencing at the nitrogen atom which is combined with the benzene 
nucleus. Ethylindazol is therefore distinguished as Iz-2-ethyl- 
indazol, and methindazol as Iz-3-methylindazol while ethyl- 
methisindazol receives the name of Iz-1-ethyl-Iz-3-methyl- 
isindazol. 

Indazol, C,H,N,, which has received this name on account of 
its relation to indol,C,H,N, is formed, together with acetic acid, 
when orthohydrazinecinnamic acid is heated : 


(0) 5 Gee O15 ROO 2 | be | 
CHK ea CHK | NNH + CH,.CO,H. 
NH.NH, No 


It is readily soluble in alcohol and hot water, and crystallizes 
in fine needles, which melt at 146°5° but sublime rapidly at 100°, 
when heated it forms a vapour which has a sweet odour, resem- 
bling that of resorcinol. It boils at 269°-270°, and separates on 
the evaporation of its ethereal solution in large, well-formed 
crystals. It combines with acids to form salts, which are decom- 
posed by water, and forms crystalline compounds with silver 
nitrate and mercuric chloride. 

Lthylindazol, C,H,N,C,H,, is formed by heating indazol with 
ethyl iodide, and is a brownish oily liquid, which smells like 
indazol and forms more stable salts. 

Nitroso-indazol, C,H;N,(NO) is obtained by the addition of 
sodium nitrite to a faintly acid, well-cooled solution of indazol, 
in the form of small, yellow needles, which crystallize from hot 
petroleum-spinit in golden-yellow, pointed needles, melting at 
73°-74°. 

Bromindazol, C,H, BrN,, is prepared by heating bromindazol- 
arboxylic acid, C,H,BrN,(CO,H) with water to 200°. It erystal- 
lizes from hot water in long, thin needles, which melt at 124°. 

Dibromindazol, C,H,Br,N,, is formed by the action of bromine- 
water on indazol, bromindazol and bromindazolcarboxylic acid. 
This last method of formation renders it probable that one atom 
of bromine is contained in the side chain. It js insoluble in 


66 AROMATIC COMPOUNDS. 


water, but dissolves readily in alcohol, &c., and crystallizes in 
needles, which melt at 239°-240° and sublime at a slightly higher 
temperature. 

2309 Methindazol, C,H,N, is formed when orthamido-aceto- 
phenone is converted into a diazo-salt and treated in solution 
with sodium sulphite; sodiwm hydrazine-acetophenonesulphonate 
is formed and rapidly changes into sodiwm methindazolsulphonate, 
which separates in lustrous plates : 


/LOCHs CCH, 
AX | SNSO,Na + H,0. 
NH—NHSO,Na NY 


Both these salts are decomposed by hydrochloric acid with 
formation of methindazol : 


CO.CH C—CH 
é i =e (OE | SNH + $0,HINa, 
N 


bh Ke 
= OFLC 


CHC 
NH—NH.SO,Na 


It is also -formed by heating <éndazolacetic acid, 
an TAG EL), EL 


CoH i /NH , which will be subsequently described. 


It is readily soluble in alcohol, tolerably in hot water, from 
which it crystallizes in long, thin needles, which rapidly become 
coloured red, melt at 113° and readily sublime. It boils at 
280°—281°, and has a similar smell to indazol; its salts are 
more stable than those of the latter, and it also combines with 
silver nitrate and mercuric chloride. 

Methylmethindazol, C,H,N,CHs, is formed by heating methin- 
dazol with methyl iodide, and crystallizes in small plates melting 
at 79°—80°. 

Lthylmethindazol, C,H,N,C,H;, is an oily liquid, volatile with 
steam, and possesses an odour resembling that of quinoline. 

Nitrosomethindazol, C,H,N,(NO), crystallizes from petroleum- 
spirit in yellow needles, melting at 60°5°. 

thylbromisindazol, C,H,BrN,, is formed by the distillation 
of ethylbromisindazolcarboxylic acid : 


OOH 
‘6 CH 
SORE FS a ey SHS 
CHK SN) es CHK DN +00, 
\,H, \G,H, 


It forms a soft, crystalline mass, melting at 48°. 


BENZOYLFORMIC ACID. 67 





Lthylmethisindazol, C,,H,,N,, was first prepared by heating 
ethylisindazolacetic acid, C,H,N,(C,H;)CH,.CO,H, and then 
from orthamido-acetophenone, which is converted into ethyl- 
amido-acetophenone by heating with ethyl iodide, the nitro- 
samine of which yields the base on reduction with zinc dust and 
acetic acid : 


CH, CH, 
| | 
CO C 
GHZ ° AE AC He SN POEL O: 
6 \w NO mE 6 NG f + 2 
| | 
C,H, C,H, 


Ethylmethisindazol boils at 234°—235°, and solidifies on 
cooling in plates which melt at 30°, have a pungent taste and are 
volatile with steam, forming a vapour which has a sharp, pene- 
trating odour, Its salts are readily soluble and are decomposed 
by a large amount of water. As a tertiary base, it does not form 
a nitrosamine, but combines with methyl iodide to form the 
salt, C,,H,,N,CH,I, which crystallizes in strongly refractive 
needles. 

Methylmethisindazol, C,5H,N,CH;, has been prepared from 
methylamido-acetophenone: it is very similar to the ethyl 
compound and melts at 36°5°. 


BENZOYL-FORMYL COMPOUNDS. 


2310 Benzoylformic acid, C,H,.;CO.CO,H. The nitril of this 
acid was obtained by Liebig and Wohler by the distillation of 
benzoyl chloride with mercuric cyanide, and named cyanbenzoyl} 
C,H;.CO.CN. They found that on heating with caustic potash 
solution it is decomposed into potassium cyanide and potassium 
benzoate. Kolbe, however, thought that the corresponding acid 
might also be formed, and, at his suggestion, Strecker investi- 
gated the reaction in this direction but only succeeded in 
obtaining hydrocyanic and benzoic acids. These products were 
also observed by Claisen, who effected the decomposition by 
heating with hydrochloric acid. When he allowed the mixture 


1 Ann. Chem. Pharm, iii. 267. 
2 Ibid. xc. 62. 


68 AROMATIC COMPOUNDS. 


to stand in the cold, however, he obtaimed benzoylformic 
acid! 

This compound, which is also known as phenylglyoxylie acid, is 
also formed by the oxidation of benzoylcarbinol and mandelic 
acid with dilute nitric acid? or potassium permanganate,? and its 
ethyl ether may be prepared by heating ethyloxalyl chloride 
with mercury phenyl : 4 


CH, coc! 


Cl CO.C,H 
Ho’ 4 a He 6145 


g | + | 
Son. coogi SCH, CO.OCEE 


Benzoylformic acid is very readily soluble in water, from which 
it is extracted by ether. On evaporation it remains as a thick, 
oily liquid, and it is separated by acids from concentrated 
solutions of its salts in this form. This liquid, which probably 
has the constitution C,H,.C(OH),.CO,H, similarly to glyoxylic 
and mesoxalic acids, solidifies in a desiccator to a radiating or 
prismatic crystalline mass, which melts at 65°—66°, and decom- 
poses on distillation into carbon monoxide and benzoic acid, a 
small quantity, however, being resolved into carbon dioxide and 
benzaldehyde. It is converted by sodium amalgam and water 
into mandelic acid, and by hydriodic acid and amorphous phos- 
phorus into phenylacetic acid. It is only gradually converted 
into benzoic acid by boiling dilute nitric acid. When sulphuric 
acid is added to its solution in benzene, which contains thiophene, 
a deep red colouration, which soon passes into a deep bluish- 
violet, is produced. On the addition of water, the substance 
which has been formed dissolves in the benzene with a carmine 
red colour. The ethers, amide and nitril of the acid give the 
same reaction.° 

When the acid is brought into contact with phenylhydrazine 
in dilute hydrochloric acid solution, phenylhydrazinebenzoylformic 
acid, C,H,(CN,H.C,H;)CO,H, separates as a yellow, voluminous 
precipitate. The acid can be easily detected by means of this 
reaction, even in very dilute solutions.® 

Most of the salts of benzoylformic acid crystallize well and 


1 Ber. Deutsch. Chem. Ges. x. 429 ; Hiibner and Buchka, ibid. x. 479 ; Buchka, 
ibid. xx. 395, 

2 Hunaeus and Zincke, zbid. x. 1486. 

3 Meyer and Baur, Ann. Chem. Pharm., ccxx. 37. 

4 Claisen and Morley, Ber. Deutsch. Chem. Ges. xi. 1596. 

5 Claisen, zbid. xii. 1505. 

6 Elbers, Ann. Chem. Pharm. cecxxvii. 340. 


BENZOYLFORMAMIDE. 69 


are soluble in water, the least soluble being the barium, lead, 
silver and mercurous compounds. 

The ethers are best prepared by dissolving the nitril in the 
corresponding alcohol and saturating the solution, which must 
be cooled by a freezing mixture, with hydrochloric acid. They 
are pleasant smelling liquids, which, as ketones, form crystalline 
compounds with acid sodium sulphite.' 

Boiling-point. 

Methyl benzoylformate, C,H;.CO.CO,.CH, . . 246°—248° 

Ethyl benzoylformate, C,H,.CO.CO,C,H; . . 256°—257° 


The homologues can only be distilled without decomposition 
under diminished pressure. ; 

Benzoylformamide, C,H;.CO.CO.N H,, is formed, together with 
the acid, by the action of concentrated hydrochloric acid on the 
nitril, and crystallizes from hot water in plates, which resemble 
those of benzoic acid, or in flat prisms, which melt at 90°—91° 
and distil almost without decomposition. It is readily soluble 
in alcohol, ether and dilute alkalis, from the last of which it is 
precipitated as the hydrate, C,H,;.CO.CO.NH, + H,O, which. 
crystallizes in clear, lustrous, microscopic, quadratic prisms, which 
are almost insoluble in ether and cold water, and lose water and 
melt at 64°—65°. It crystallizes from tolerably hot water 
without change, but the anhydrous compound is deposited from 
a solution in boiling water, and is also obtained by the evapora- 
tion of the alcoholic solution. This hydrate has probably the 
constitution C,H,.C(OH),CO.NH,,. 

When an alkaline solution of benzoylformamide is slowly run 
into an excess of hydrochloric acid, an isomeric, or more probably 
polymeric, compound separates out as a powder, which crystallizes 
from alcohol in prisms, which melt at 134°—135°, but after 
being kept at this temperature for a short time do not solidify 
until the temperature has fallen to 90°—80°, the normal com- 
pound being reproduced; it is also converted into the normal 
compound by boiling with water. The constitution of this 
substance is perhaps represented by the following formula :? 


C,H,.0.C0.NH, 
0’ SO 
O,H,,.6.CO.NH, 


1 Ber. Deutsch. Chem. Ges. xii. 626. 
2 Claisen, 2bid. x. 1498 ; xii. 682. 


ed 


70 AROMATIC COMPOUNDS. 


It may also, however, be similar to that of paraldehyde 
(Part I, p. 479). 

Isonitrosophenylacetic acid, C;H;.C(N.OH)CO,H, is formed by 
the action of hydroxylamine on benzoylformic acid, and is a 
crystalline mass which is readily soluble in water, alcohol and 
ether, has an aromatic odour and melts at 127°—128°. It is 
converted into amidophenylacetic acid by tin and hydrochloric 
acid.} 

Ethyl isonitrosophenylacetate, C,H,.;CCNOH)CO.OC,H,, is 
obtained by the action of hydroxylamine on ethyl benzoyl- 
formate, and crystallizes from boiling water in long, lustrous 
needles, melting at 112°—113°? 

2311 Benzoylformonitril, C,H;.CO.CN, is prepared, as already 
mentioned, by the distillation of benzoyl chloride with mercuric 
cyanide. In order to free it from the latter, it is washed with 
warm water until a portion of the washings does not give a 
black colouration with sulphuretted hydrogen. Wohler and 
Liebig described it as a liquid possessing a penetrating odour 
resembling that of oil of cinnamon, but producing a flow of tears, 
and having a sharp but sweet taste, with an after taste like that 
of hydrocyanic acid. Strecker found, however, that it solidifies 
after some time * and forms splendid, long, transparent asym- 
metric prisms,* melting at 33°—34". 

By the action of zine and hydrochloric acid it is converted 
into benzaldehyde and hydrocyanic acid. Alkalis decompose it 
into the latter and benzoic acid, while hydroxylamine converts it 
into dibenzhydroxamic acid (Part IV., p. 209). In these reactions, 
therefore, it behaves in an exactly analogous manner to benzoyl 
chloride (Muller). When its ethereal solution is treated with 
zinc ethide, benzoic acid, ethylphenylketone C,H,.CO.C,H,, and 
zinc cyanide are formed, together with a small quantity of 
benzocyanidin, C,,H,,NO,, which crystallizes from alcohol in 
colourless needles, melting at 123°—124°® 

Phenyldichloracetic acid, C,H;.CCl1,CO,H, is formed by the 
action of chlorine on phenylchloracetic acid in the sunlight,’ 
and its ethyl ether is obtained by treating ethyl benzoylformate 
with phosphorous chloride. This is readily saponified by 


1 Miller, Ber. Deutsch. Chem. Ges. xvi. 1617. 

2 Gabriel, zbid. xvi. 517. 

3 Ann. Chem. Pharm. xc. 62. 

4 Bodewig, Ber. Deutsch. Chem. Ges, xii. 626. 

> Kolbe, Ann. Chem. Pharm. xeviii. 344. 

6 Frankland and.Louis, Journ. Chem. Soc. 1880, i. 742. 
” Radziszewski, Ber. Deutsch. Chem. Ges. ii. 209. 


DERIVATIVES OF BENZOYLFORMIC ACID. 71 





alcoholic potash, the potassium salt, which crystallizes in 
prisms and is very soluble in water and alcohol, being formed. 
The free acid is liberated by the addition of hydrochloric acid to 
an aqueous solution of this salt, and remains, after extraction 
with ether and evaporation of the latter, as a thick, oily liquid, 
which solidifies after standing for some time in a desiccator, to 
small, very deliquescent tablets or cubes.? 

Lihyl phenyldrchloracetate, C,H;.CCl,.CO,.C,H,, is a heavy, 
pleasant smelling liquid, which boils at 263°—266°. 

Phenyldichloracetonitril, C,H,.CCl,.CN, is formed by the 
action of phosphorous chloride on benzoylformonitril,and is a 
transparent colourless liquid, which has a characteristic odour, 
boils at 223°—224°, and is decomposed by caustic potash into 
potassium benzoate, cyanide and chloride.? 

Metanitrobenzoylformic acid, C,H,(NO,)CO.CO,H, is prepared 
from the corresponding amide by heating it in tolerably dilute 
alkaline solution on the water bath until all smell of ammonia 
has disappeared. The solution is then acidified with nitric acid 
and extracted with ether, the acid being left on the evaporation 
of the latter as a yellowish, viscid syrup, which solidifies in a 
desiccator to small, short prisms. It melts at 77°—78°, is readily 
soluble in water, alcohol and ether, has a very bitter taste, which 
also characterizes its salts, and gives the same reaction as 
benzoylformic acid with sulphuric acid and benzene containing 
thiophene.* 

Metamtrobenzoylformamide, C,H,(N O,)CO.CO.NH,, is formed, 
together with a large amount of metanitrobenzoic acid, when a 
mixture of equal parts of benzoylformamide and potassium 
nitrate is brought into ten parts of sulphuric acid at — 10° 
and may also be obtained by the action of the most concentrated 
cold hydrochloric acid on the nitril. It is scarcely soluble in 
cold, more readily in boiling water, from which it crystallizes in 
white or yellowish, narrow prisms, which melt at 151°—152°, 

Metanitrobenzoylformonitril, C,H,(NO,)CO.CN, is best pre- 
pared by the distillation of metanitrobenzoyl chloride with 
mercuric cyanide under diminished pressure (Claisen and 
Thompson). It is also formed in small quantity, together 
with a large amount of metanitrobenzoic acid, when a mixture 


1 Claisen, Ber. Deutsch. Chem. Ges. xii. 630. 
2 Ibid. xii. 626. 

3 Claisen and Thompson, 7bid. xii. 1942. 

4 Thompson, zbid. xiv. 1185. 


271 


72 AROMATIC COMPOUNDS. 





of benzoylformonitril and potassium nitrate is brought into 
well-cooled sulphuric acid (Thompson), and is a thick, light 
yellow liquid, which has a faint odour resembling that of 
benzoylformonitril, boils at 230°—231°5° under a pressure of 
142—147 mm. and does not solidify at — 17°. It dissolves 
in concentrated caustic potash solution with formation of 
hydrocyanic acid and metanitrobenzoic acid. 

Orthonitrobenzoylformic acid, C,H,(NO,)CO.CO,H, is prepared 
from its amide in a similar manner to the meta-acid. It 
separates from an alkaline solution on the addition of hydro- 
chloric acid as a pale yellow oil,- which soon solidifies. It 
dissolves in every portion in tolerably hot water and crystallizes 
on cooling, frequently only after standing for some time, in 
long, hair-like, lustrous prisms, which probably have the formula, 
C,H,(NO,)C(OH),CO,H, and melt at 46°—47°. They lose 
water over sulphuric water and then melt with decomposition 
at 122°—123°.1 | 

Orthonitrobenzoylformamide, C,H,(NO,)CO.CO.NH,, is formed 
by the action of cold, fuming hydrochloric acid on the nitril, and 
crystallizes from hot water in small, white prisms, melting at 189°. 

Orthonitrobenzoylformonitril, C,H,(NO,)CO.CN, is obtained 
by heating orthonitrobenzoyl chloride with silver cyanide to 
100°, and crystallizes from hot petroleum-spirit in white, strongly 
lustrous prisms, melting at 54°.? 

Orthohydroxybenzoylformic acid, C,H,(0H)CO.CO,H, has been 
prepared from isatic acid (p. 77) by means of the diazo- 
reaction. It crystallizes from a mixture of benzene and petro- 
leum spirit in concentric groups of needles, melting at 43°—44°, 
and is converted into orthohydroxymandelic acid by water and 
sodium amalgam. 

Veratroylearboxylic acid, C,H,(OCH;),CO.CO,H, is formed, 
together with veratric acid (Part IV., p. 354) by the oxidation of 
methyleugenol, C,H,(OCH,),C,H;, with potassium perman- 
ganate. It dissolves very readily in water and alcohol, and 
crystallizes from anhydrous benzene in fine needles, melting at 
138°—139°, while in the presence of water, transparent tablets 
are formed, which effloresce in the air. It is converted into 
veratric acid by further oxidation, and into protocatechuic acid 
by fusion with potash.! | 

1 Claisen and Shadwell, Ber. Deutsch. Chem. Ges. xii. 1945. 
2 Ibid. xii. 350. 


3 Baeyer and Fritsch, ibid. xvii, 973. 
4 Tiemann and Matsmoto, ibid. xi. 141. 


ISATIN. 73 





Metamidobenzoylformic acid, C,H,(NH,)CO.CO,H, is prepared 
by the reduction of the nitro-acid with ferrous sulphate in 
alkaline solution. It is only slightly soluble in cold water and 
crystallizes from boiling water in strongly lustrous needles or 
prisms, which are almost insoluble in alcohol and ether, and 
decompose on heating. The hydrochloride crystallizes in con- 
centrically grouped, flat prisms. This acid also gives the 
characteristic reaction with sulphuric acid and _ benzene 
containing thiophene (Claisen and Thompson). 


ISATIN, C,H,NO,. 


2312 This compound, the name of which is derived from 
Isatis tinctoria, the woad or European indigo plant, was simul- 
taneously discovered by Erdmann and Laurent in 1841. The 
former prepared it by heating indigo-blue, C,,H,).N.,O,, with a 
dilute solution of chromic acid, and the latter showed that 
nitric acid can be employed as the oxidizing agent.2, They also 
found that it is converted by the action of alkalis into ¢satie acid, 
C.H,NO,, and that on treatment with chlorine and bromine it 
yields substitution-products which had been previously prepared 
by Erdmann from indigo.* 

Hofmann then observed that isatin is converted into aniline by 
fusion with caustic potash : 


C,H,NO, + 4KOH = C,H,N + 2K,CO, + H;. 


In this way he prepared the substituted anilines from the 
substitution-products of isatin, the discovery of these being of the 
greatest importance for the development of the theory of sub- 
stitution (Part I, p. 15). He also found that dilute nitric acid 
oxidizes isatin to nitro-salicylic acid, which had previously been 
prepared from indigo (Part IV., p. 815), and subsequently showed 
that this substance is also formed when isatin is suspended in 
water and treated with nitrous acid,* whilst benzoic acid is 
formed in the presence of alcohol.? It followed from these 
facts that the nitrogen atom in isatin is directly combined 


1 Journ. Prakt. Chem. xxiv. 10. 2 Ann. Chim. Phys. [8] iii. 372. 
3 Journ. Prakt. Chem. xix. 320, 4 Ann. Chem. Pharm. cxv. 280. 
> Baeyer and Knopp, zbzd. exl. 1. 


74 AROMATIC COMPOUNDS. 


with a carbon atom of the benzene nucleus, but no further 
conclusions as to the constitution of this substance could be 
drawn. The study of its reduction-products, which was carried 
out by Laurent, and subsequently by Schiitzenberger, was also 
fruitless of results in this direction, since the composition of these 
products is more complicated than that of isatin itself. 

Baeyer and Knop, however, were more successful and their 
investigations led to the determination of the constitution both 
of isatin and indigo. By the addition of hydrogen and the 
successive removal of the two atoms of oxygen they prepared 
the following compounds, which have already been described : 


Tsatin = sips \cr ogpecee MRL GC) 
Dioxindol, . . . . C,H.NO, 
Oxindol ite me C,H,NO 
Lew Pes A CTE: 


Baeyer then found that oxindol is the anhydride of orthamido- 
phenylacetic acid. 

In conjunction with Knop, he had previously prepared a 
compound by the action of nitrous acid on oxindol, which they 
considered to be nitroso-oxindol, but which subsequently proved 
to be the isonitroso-derivative of isatin. By the reduction of this, 
Baeyer obtained amido-oxindol, which was converted into isatin 
by oxidation. He assigned the following formule to these 
compounds : * 


Nitroso-oxindol. eae a see 
NH 

He >CO ont Sco KC pease 
CH(NO) CH(NH,) 


Kekulé had previously, in 1869, proposed this formula for 
isatin,2 and it was confirmed in 1879 by the researches of 
Claisen and Shadwell, who found that orthamidobenzoylformic 
acid is identical with isatic acid, isatin being, therefore, its 
anhydride.’ 

aN. Ete pring 
Ven = CH te + H,0. 
CO.CO.OH CO 

It followed from this that oxindol, dioxindol and isatin are the 

anhydrides, or, as Baeyer terms them, the /actams of orthamido- 


1 Ber. Deutsch. Chem. Ges. xi. 1228. 2 Ibid. ii, 748. 3 Ibid. xii. 350. 


PREPARATION OF ISATIN. 75 


acids. An extended series of investigations, however, has led 
him to the view that isatin does not contain the imido-group 
but the hydroxyl-group, its constitution being expressed by the 
following formula :1 


O 
soot des 
CHK  DO0n 


It is therefore the lactim of isatic acid, orthamidobenzoyl- 
formic acid ; its lactam, which Baeyer names pseudoisatin, is not 
known in the free state, although some of its derivatives have 
been prepared. 

He gives the general name of pseudo-compounds to com- 
pounds which do not exist in the free state, but immediately 
pass into an isomeric, stable form.” 

It may here be mentioned that Blyth and Hofmann had 
endeavoured in 1845 to convert styrolene into isatin. They 
hoped to obtain the base, C,H,N, by the reduction of nitro- 
styrolene (p. 35), and expected that this would yield compounds 
of the indigo series on oxidation, among which isatin might 
occur ; their experiments, however, proved unsuccessful. 

Various methods of procedure have been proposed for the 
preparation of isatin from indigo. 

According to Knop, 500 grms. of very finely powdered indigo 
are heated to boiling with 1°5 litres of water in an evaporating 
basin of 10 litres capacity, since the reaction causes considerable 
frothing, and to this the necessary amount of nitric acid, of 
sp. gr. 1°35, is added as rapidly as the frothing will allow. When 
the indigo contains 45 per cent. of colourimg matter, 320 grms. 
of acid must be employed, 350 grms. if the indigo contain 
50 per cent., &c.* 

According to Sommaruga, 50 grms. of good indigo, containing 
60—70 per cent. of the colourmg matter, are ground as fine 
as possible and stirred with water to a thin paste, which is then 
heated to boiling and treated gradually with a concentrated 
solution of 30 grms. of chromium trioxide. The boiling is con- 
tinued until the light foam has disappeared and large bubbles 
appear on the surface of the liquid. When everything has been 
previously prepared, four operations can be conducted simul- 


1 Ber. Deutsch. Chem. Ges. xv. 2100. 

2 Ibid. xix. 162 ; see also vol. iii. part iv. p. 518. 
3 Ann. Chem. Pharm. liii. 301. 

4 Journ. Prakt. Chem. xcvii. 86. 


76 AROMATIC COMPOUNDS. 


taneously and completed in ten minutes. The boiling solutions 
are then filtered and deposit the isatin, accompanied by a little 
brown resin, on cooling. The chromium sesquioxide, which 
remains in the filter, is extracted two or three times with boiling 
water and the extracts added to the mother-liquors, which are 
then either concentrated, a somewhat impure isatin being thus 
obtained, or extracted with ether after partial evaporation, isatin 
being taken up by ether from an aqueous solution, although in 
the solid state it 1s quite insoluble.t 

The crude isatin is then purified by Hofmann’s method,? 
according to which it is dissolved in cold caustic potash and the 
solution treated with hydrochloric acid as long as a dark-coloured 
precipitate is formed. As soon as a small portion of the filtered 
liquid appears of a pure yellow colour and gives a bright red 
precipitate on the further addition of hydrochloric acid, the resin 
is filtered off and the isatin completely precipitated, filtered and 
washed with a little water. The yield amounts to about 16—18 
per cent. of the indigo-blue employed. 

Isatin is also obtained when orthonitrophenylpropiolic acid, 
which is manufactured on the large scale, is boiled with alkalis, 
and this reaction takes place so readily and with so good a yield 
that Baeyer considers it to be the best method of preparation.% 
It is also formed when a solution of orthonitrophenylpropiolic 
acid in sulphuric acid is poured into water. The isomeric isato- 
genic acid is first formed, but immediately decomposes into isatin 
and carbon dioxide : 


C=0.C0,H CO 
CHK ios CHL »C.C0,H es 
NO, NZeA 
CO 
CHK : So.on + CO,. 


Properties.—Isatin is slightly soluble in cold, readily in boiling 
water, forming a yellowish red solution, and also dissolves freely 
in hot alcohol ; it crystallizes in dark red, monosymmetric prisms, 
or, when rapidly deposited, in small, yellowish red, lustrous 
needles, which melt at 200°—201°° and partially sublime when 
carefully heated. It imparts an unpleasant, adhering smell to 
the skin. 


1 Ann. Chem. Pharm. exe. 367. 2 Toid. liii. 11. 
3 Ber. Deutsch. Chem. Ges, xiii. 2259 ; see also Forrer, ibid. xvii. 976. 
4 Baeyer, ibid. xiv. 1741. 5 Baeyer, ibid. xv. 2094, 


ISATIC ACID. 77 


—_—_———__ __. ee 


When a solution of isatin in sulphuric acid is shaken up 
with benzene, which contains thiophene, a deep blue solution is 
formed (Part IV., p. 75), from which water precipitates indo- 
phenin, C,,H,NOS, as a blue powder.1 

A blue colouring matter, similar to indigo, is also formed when 
pyrrol and dilute sulphuric acid are added to an aqueous solution 
of isatin,or when pyrrol alone is added to a boiling solution of 
isatin in glacial acetic acid. 

Isatin dissolves in caustic potash and ammonia forming a 
dark red solution; on the addition of silver nitrate, a dark red 
precipitate of silver isatin, C,H,AgNO,, is obtained.* When 
alcoholic solutions of isatin And silver nitrate, both containing 
ammonia, are mixed, a crystalline precipitate of C,H,(NH,Ag) 
NO,, of the colour of wine lees, is formed (Laurent). 

2313 Isatic acid or Orthamidobenzoylformic acid, C,H,(NH,) 
CO.CO,H, is formed, according to Erdmann and Laurent, by 
heating an alkaline solution of isatin, the red colour of the solution 
changing to yellow. Baeyer explains this change by assuming 
that the lactim is first converted into the lactam : 


"CoH + Oe Oh  ScooHy) = 


CO—CO.0H 
ond. "Soo + 0 = GH 
\NH \NH,. 


Claisen and Shadwell, as previously mentioned, obtained this 
acid by reducing orthonitrobenzoylformic acid in alkaline solution 
with ferrous sulphate. It is left after the evaporation of its solution 
in vacuum as a white, indistinct crystalline powder. Its aqueous 
solution becomes coloured brownish-yellow on warming and 
then deposits isatin. Its salts are more stable, the potassium 
salt forming light yellow crystals. 

Barium wsatate, (CsH,NO,),Ba, crystallizes in short, colourless 
prisms, which are only slightly soluble in water. 

Silver isatate, C,H,NO,Ag, separates in yellow prisms when 
hot solutions of the potassium salt and silver nitrate are mixed. 

Lsatinsulphurous acid is not known in the free state ; its salts 


HC 


5 aeyer and Lazarus, Ber. Deutsch. Chem. Ges. xviii. 2637. 
2 V. Meyer, ibid. xvi. 1478 ; Ciamician and Silber, zbid. xvii. 142 ; Meyer and 
Stadler, bid. xvii. 1034. 
% Laurent, Journ. Prakt. Chem. xxxv. 108 ; Baeyer, Ber. Deutsch. Chem. Ges. 
xv. 2093. 


78 AROMATIC COMPOUNDS. 


are formed by boiling isatin with the acid alkali sulphites, with 
which, like all other ketones, it combines. 

Potassium isatinsulphite, C,H,NO,SO,KH+2H,0, is also 
formed when a solution of potassium isatate is saturated with sul- 
phur dioxide and evaporated. It crystallizes in pale yellow tablets, 
which are only slightly soluble in water and are slowly decom- 
posed by hydrochloric acid in the cold, but rapidly on heating. 

2314 Chlorisatin, CgH,CINO,, is formed when chlorine is 
allowed to act upon indigo or isatin suspended in water (Erdmann, 
Laurent). It is best obtained by suspending isatin in boiling 
water and passing in chlorine, in the sunlight, until the crystals 
have assumed a pure orange-yellow colour. In this way, as 
Erdmann had previously stated, the product is obtained quite free 
from dichlorisatin (Hofmann), while, according to Dorsch, both 
substitution products are formed.! 

Chlorisatin crystallizes in small, lustrous plates or transparent 
orange-yellow prisms, isomorphous with those of isatin, which 
dissolve in 200 parts of water at 100° and about 1,100 parts at 
0°, and in 220 parts of alcohol of sp. gr. 0°830 at 14°. It melts 
at 243° with decomposition and partially sublimes in transparent 
needles, the greater portion however, being decomposed. Its 
powder causes sneezing ; it has a bitter taste and is quite odour- 
less, but its solution imparts a very unpleasant and exceedingly 
persistent smell to the skin (Erdmann). Like isatin it gives a 
crystalline silver ammonium compound, which is of the colour of 
wine lees (ze de vin). It also forms compounds with the acid 
alkali sulphites. When a solution of chlorisatin is treated with 
caustic potash, it first becomes deep red and then pale yellow, 
while, when the solid compound is treated in the same way, it 
becomes almost black and gradually dissolves, more rapidly on 
heating, forming a lght yellow solution. Chorisatic acid, 
C,H,Cl(NH,)CO.CO,H, is thus formed, but is very unstable 
and decomposes immediately into chlorisatin and water when 
liberated from its salts. 

Potassvum chlorisatate, C,H,Cl(N H,)CO.CO,K, crystallizes in 
light yellow needles or nacreous scales, is readily soluble in water, 
with difficulty in alcohol and has a very bitter taste. Other salts 
have been prepared from this by double decomposition, the 
following being characteristic. 

Lead chlorisatate, (C,H,Cl.NH,.CO.CO,),Pb+2H,0O, forms a 
lustrous yellow, gelatinous precipitate, which soon becomes 

1 Journ. Prakt. Chem. [2] xxxiii. 49. 


SUBSTITUTION PRODUCTS OF ISATIN. 79 


crystalline and assumes a splendid scarlet-red colour. It forms 
a yellow solution in boiling water and separates on cooling in 
scarlet granules. 

The copper salt is a yellowish brown precipitate, which 
suddenly becomes deep blood-red coloured and is deposited as a 
heavy, granular powder. This remarkable property has been 
carefully investigated by Erdmann in the case of the corre- 
sponding salt of dichlorisatic acid, which behaves in a precisely 
similar manner. - 

Dichlorisatin, C,H,C1,NO,, is formed, together with chlorisatin, 
by the action of chlorine on indigo suspended in water and is 
separated from the mono-substitution product by recrystallization 
from alcohol, m which it is much more readily soluble. It 
crystallizes in small, red plates, needles or four-sided prisms, 
melts at 186° (Dorsch), dissolves at 14° in 29°3° of alcohol, of sp. 
gr. 0°830, and combines with the acid alkali sulphites. 

It forms a deep red solution in caustic potash, which becomes 
pale yellow on heating, dichlorisatic acid, C,H,Cl,(N H,)CO.CO,H 
being formed. This substance is precipitated by acids from 
the concentrated solution as a yellow powder, which is readily 
soluble in water and decomposes at 100° into water and dichlor- 
isatin; this decomposition takes place in solution at 60°, the 
light yellow colour changing to reddish yellow and dichlorisatin 
being deposited on cooling. 

Potassium dichlorisatate, C,H,Cl,(N H,)CO.CO,K + H,0, erys- 
tallizes from alcohol in light yellow plates or needles, which have 
a metallic lustre. 

Its solution gives a yellow precipitate with lead acetate, which 
does not change its colour. 

Copper dichlorisatate, (C,H,Cl,(N H,)CO.CO,), Cu, is obtained 
as a precipitate resembling ferrous hydroxide, which after a few 
seconds becomes flocculent and coloured pale greenish yellow 
and is finally deposited as a heavy, carmine-red, granular powder. 
A microscopic examination shows that hair-like or foliaceous 
groups of crystals are formed when the greenish colouration 
appears, and that when the colour changes to red, which appears 
first at isolated spots and is then rapidly transmitted through 
the entire mass, these crystals are replaced by irregular, 
transparent, red granules. 

The dry, carmine-red powder which is well adapted for use as 
a pigment, takes a gold lustre when pressed with a hard body 
(Erdmann), 


80 AROMATIC COMPOUNDS. 


Bromisatin, C,H,BrNO,, was obtained by Erdmann in small 
quantity, accompanied bya much larger amount of dibromisatin, 
by the action of bromine on indigo, while Laurent could only 
obtain the di-substitution product by the action of bromine on 
isatin. Hofmann, however, found that it is formed when isatin 
is treated with bromine water, even in the sunlight. It cor- 
responds to chlorisatin in all its properties, and the similarity 
between these substances is so great that Hofmann referred to 
Erdmann’s and Laurent’s papers on chlorisatin for an account of 
its chemical behaviour! It melts at 255° (Baeyer). 

Bromisatic acid and its salts, which have been examined by 
Gericke, also resemble the corresponding chlorine compounds in 
every respect.” 

Dibromisatin, CsH,Br,NO,,is best prepared, according to Baeyer, 
by treating a solution of isatin in glacial acetic acid, saturated 
at 100°, with about twice as much bromine as is necessary for the 
formation of dibromisatin and then heating for 15-20 hours on the 
water bath. It separates on cooling in orange-coloured needles, 
which are purified by conversion into potassium dibromisatate, 
which is only slightly soluble in water.® 

Dibromisatin crystallizes from alcohol in four-sided prisms, 
which melt at 250°, and is much more readily soluble than the 
monobromo-compound. According to Baeyer, this is obviously due 
to the fact that the first bromine atom takes the para-position 
and the second the ortho-position to the nitrogen atom. The 
effect of the bromine atom in the ortho-position is also 
shown by the fact that the salts of dibromisatin and di- 
bromisatic acid itself are much more stable than the derivatives 
of bromisatin. The second bromine atom, however, as will 
subsequently be shown, is actually situated in the meta- 
position. 

Potassium dibromisatin, C,H,K Br, N O,, is obtained, according to 
Laurent, by the addition of alcoholic potash to a hot alcoholic 
solution of isatin, in the form of black spangles, which appear 
blue by transmitted light. It is also formed as a bluish violet 
powder by the action of dilute caustic potash solution on ethyl- 
dibromisatin (Baeyer). 

Silver dibromisatin, C,5H,AgBr,NO,, is prepared in a similar 
manner to silverisatin and is a brownish violet powder (Baeyer). 

Dibromisatic acid, C,H,Br,(NH,)CO.CO,H, is formed by the 


1 Ann. Chem. Pharm. liii. 40. 2 Journ. Prakt. Chem. xcv. 176. 
3 Ber. Deutsch. Chem. Ges. xv. 2098. 


ETHERS OF ISATIN. 81 





decomposition of its potassium salt and is a yellow powder, 
readily soluble in water, which is converted into erbromusatin by 
drying. 

Potassium dibromisatate, C,H,Br,(NH,)CO.CO,K+H,0, is 
formed by heating dibromisatin with caustic potash and crystallizes 
in lustrous, straw-yellow needles, which are only slightly soluble 
in water. The copper salt behaves in a similar manner to that 
of dichlorisatic acid (Erdmann). 

2315 Lthers of rsatin and the bromisatins are obtained by the 
action of alcoholic iodides on the silver on at 


AX ~ COag atvaenE sa at” ° Scoot, 4, Apt, 
_n=7 


Methylisatin, C,H,(CH,)NO,, crystallizes from hot benzene in 
tolerably large, blood-red prisms, melting at 101°—102°, and is, 
like the salts of isatin, a very unstable substance, changing 
spontaneously after a short time, and frequently immediately after 
its preparation, into methylisatoid, C,,H,,N,O,, a yellow powder, 
which crystallizes from alcohol in small yellow needles, melting 
with decomposition at 219°, and is converted into isatic acid by 
boiling with caustic soda. 

Methylbromisatin, C,A,Br(CH,)NO,, forms blood-red needles, 
which melt at 147° and readily change into methylbromisatoid, 
which melts at 230°—231°. 

Hihylbromisatin, C,H,Br(C,H,)NO,, crystallizes from hot 
benzene in long, blood-red, prismatic needles, melting at 107°—109°. 
On the addition of caustic potash solution to its alcoholic solution, 
it is first coloured reddish violet and then yellow, bromisatic acid 
being formed. When preserved for some time, it changes into 
ethylbromisatoid, C,,H,,Br,N,0,, which is more rapidly formed 
when the original ether is dissclved in acetic anhydride. In this 
case the isatoid is deposited after two days in orange-yellow 
needles, which melt with decomposition at 244°—245° and dissolve 
in dilute, boiling caustic potash solution with a red colour, 
which soon changes to yellow, bromisatic acid being formed. 

The constitution of these isatoid ethers is quite unknown ; 
their empirical formule correspond to compounds of isatin or 
bromisatin with the ethers of these : 


C,H,NO, + C,H,(CH;)NO, = 0,,H,,.N.0,. 
C.H,BrNO, + C,H,Br(C,H,)NO, = C,,H,.Br,N,0,. 
1 Baeyer and Oekonomides, ibid. xvi. 2093. 


82 AROMATIC COMPOUNDS. 


Ethyldibromasatin, C,H,Br,(C,H,)NO,, - crystallizes from 
alcohol in blood-red, Raheeal ageregates, containing alcohol. of 
crystallization, which is soon hae in the air ; the eee become 
dull and then melt at 87°—89°. Dilute ee potash converts it 
into potassium dibromisatin. It does not change into an isatoid 
ether either spontaneously or on treatment with acetic anhydride. 

Ethyl dibromisatate, C,H,Br,(NH,)CO.CO,.C,H,, is formed by 
the action of ethyl iodide on silver dibromisatate and crystallizes 
in yellow tablets, which melt at 105° and are not converted into 
ethyl dibromisatin, but into dibromisatin on heating : 


NH 
C,H ; = OBC NC.OH + HO.C,H,. 


Br, 
* *\\00.C0.0C,H, 


2316 Nitro-isatin, C,H,(NO,)NO,, is obtained by the addition 
of the calculated quantity of potassium nitrate to a solution of 
isatin in ten parts of sulphuric acid, which is cooled by a freezing 
mixture. After standing for some time, the liquid is poured on to 
ice and the separated product crystallized from alcohol. It forms 
yellow needles, which crystallize in rosette-shaped aggregates, 
melt at 226°—230° and form a reddish-yellow solution in caustic 
potash, which does not become lighter coloured on heating! 

Nitrobromisaiin, CgH .Br(NO,)NO,,; is prepared from promise 
in a similar manner oi nitro-isatin and crystallizes from alcohol 
in orange-yellow, warty masses, composed of small plates, which 
melt with decomposition at 237°. It forms a dark red solution 
in caustic soda, an orange-yellow precipitate being then produced, 
so that the colour of the solution becomes lighter. This pre- 
cipitate dissolves when the solution is boiled and does not separate 
out again on cooling.” 

Isatinsulphonie acid, C,H,NO,.80,H+2H,0. When indigo 
is dissolved in fuming sulphuric acid, indigo-blue sulphuric acid 
or indigotindisulphonie acid, C,,H,N,O,(SO,H),, is formed, the 
sodium salt of which is brought into the market under the name 
of indigo-carmine. Gustav and Adolph Schlieper obtained 
isatinsulphonic acid, or as they named it dsatinsulphurie acid, by 
the oxidation of this with hot, dilute sulphuric acid and potas- 
sium dichrowfate. They prepared the potassium salt by the 
addition of potassium nitrate to the hot, filtered solution, con- 


1 Baeyer, Ber. Deutsch. Chem. Ges. xii. 1312. 
2 Dorsch, Journ. Prakt. Chem. [2], xxxiii. 53. 


ISATIN CHLORIDE. 83 


verted this into the barium salt and finally liberated the free acid 
with sulphuric acid.! It forms a yellow, crystalline mass, which 
has a silky lustre and a strongly acid taste, dissolves readily 
in water, with more difficulty in alcohol, and becomes anhydrous 
at 100°. Nitric acid does not attack it, even on boiling, while 
potassium chlorate and hot hydrochloric acid convert it gradually 
into chloranil. Its solution dyes silk and wool orange-red. 

Potassium isatinsulphonate, C,H,NO,SO,K + H,O, forms a 
crystalline powder, consisting of golden-yellow needles, which 
dissolve in about 20 parts of cold water, more readily in hot 
water, and are not attacked by boiling concentrated hydrochloric 
acid. 

Sodium isatinsulphonate, CsH,NO,SO,Na + 2H,0, is ob- 
tained by the addition of a large amount of common salt to the 
hot, saturated solution of the potassium salt. It crystallizes 
on cooling in large, bright red tablets. 

Barium isatinsulphonate, (C,H,NO,SO,),Ba + 4H,O, is formed 
when a barium salt is added to an isatinsulphonate in acid 
solution and even when the free acid is added to a solution 
of barium chloride or nitrate. It forms brilliantly lustrous, 
scarlet-red, crystalline scales, which are insoluble in alcohol 
and slightly soluble in cold, more readily in hot water. 

Sulpho-isatic acid, C,H3(NH,)(SO;H)CO.CO,H. The salts of 
this acid are formed when the preceding compounds are heated 
with alkalis. They are of a yellow colour, crystallize well, and 
are reconverted into isatinsulphonates by hydrochloric acid. 

Isatin chloride, C.SH,NOCI, is obtained by heating isatin with 
benzene and phosphorus chloride. It crystallizes on cooling in 
small, brown needles, forms blue solutions in ether, alcohol, &c., 
rapidly decomposes in moist air and is converted into isatin by 
caustic potash, while ammonium sulphide converts it into indigo- 


blue :? 
oC HC a ~~ Doct Saree 


CO 
AAs eh Cea 
A a Doan OH, + 2HCl, 


Bromisatin chloride, C,H,BrNOCI, is prepared in the same 
manner from bromisatin and crystallizes in small, reddish-brown 


1 Ann. Chem. Pharm. exx. 1. 
2 Baeyer, Ber. Deutsch. Chem. Ges, xi. 1296 ; xii. 456. 


84 AROMATIC COMPOUNDS. 


lustrous needles, which form solutions of this colour in alcohol, 
ether and benzene and are converted into bromindigo by the 
action of hydriodic acid." 

2317 Methylpseudo-isatin, C,H,O,NCH,, is formed when 
methylindol, C,H,NCH,, or methylindolcarboxylic acid, C,H; 
(NCH,)CO,H, is treated with solution of sodium hypobromite 
and the crystalline bromine compound, C,H,Br,NCH,, which is 
formed, decomposed with caustic soda solution. The formation 
of the methylpseudo-isatin can be simply aaa by the 
following equation : 


On Ree Yous sBOH =O,  \c04SHBrHH,0 


' i 
CH, CH, 


It can also be obtained by the use of sodium hypochlorite.’ 
It crystallizes from hot water in splendid red needles, which 
melt at 134°, and in its other properties resembles the ethyl 
compound, which has been more carefully investigated. 

Ethylpseudo-rsatin, C,H,O,.NC,H,, which is prepared in a 
similar manner from ethylindolcarboxylic acid, was first obtained 
by Baeyer by dissolving ethylpseudo-isatin-a-ethyloxime (p. 94) 
in acetic acid and treating it with zinc dust, the mixture being 
well cooled, until the yellow colour of the solution disappeared. 
Tt was then diluted with water and boiled with ferric chloride 
for five or ten minutes. The ethylpseudo-isatin was then 
extracted with ether, removed from the ethereal solution by 
caustic soda, liberated by acidification and again extracted with 
ether. It remained on evaporation in blood-red tablets, similar 
to those of azobenzene.® 

It is readily soluble in alcohol and hot water, with greater 
difficulty in ether, melts at 95° and. volatilizes when more 
strongly heated, with formation of a greenish-yellow vapour. It 
dissolves in alkalis to a yellow solution, a salt of ethylisatic acid, 
C,H,[N(C,H,)H]CO.CO,H, being formed, whereas isatin itself 
is first converted into its violet salt and then into the yellow 
isatate. This salt yields ethylpseudo-isatin on decomposition 
by acids. 
| 1 Ber. Deutsch. Chem. Ges. xii, 1815. 


? Fischer and Hess, ibid. xvii. 5638. 
3 Ibid. xvi. 2198. 


PSEUDO-ISATIN DERIVATIVES. 85 


' Barium ethylisatate, (C,,H,,NO,),Ba, is formed by dissolving 
ethylpseudo-isatin in baryta water and crystallizes from the 
concentrated solution in pure yellow, lustrous needles. When 
silver nitrate is added to its solution, silver ethylisatate separates 
in flat, yellow needles, which are slightly soluble in water. 

Ethylpseudo-isatin yields an indophenin with sulphuric acid 
and benzene containing thiophene, which forms a blue solution in 
ether and is thus distinguished from that given by isatin, which 
is absolutely insoluble in ether. 

It is not attacked by concentrated hydrochloric acid even 
at 150° and therefore contains the ethyl group very firmly 
combined, while ethylisatin is saponified by dilute alkalis even 
in the cold (Baeyer). 

Benzylpseudo-isatin, C,H,O,NCH,.C,H;, has been prepared by 
the oxidation of benzylindol (p. 39) and crystallizes from hot 
water in silky, red needles, melting at 131°4 

Acetylpseudo-isatin, C,H,O,NCO.CH,, is formed by heating 
isatin with acetic anhydride : 


CO.CH, 
H, > OH + 0% 
ay \co.CH, 
7 00.s 
ER oie Doo 
+H0.C0.0H, 

HC _n-” ~~ \0.CO.CH, - HC 

| ie 

CO.CH, CO.CH, 


It crystallizes from benzene in yellow, prismatic needles, which 
are slightly soluble in cold water, readily in alcohol and melt at 
141°, On boiling with water, or more rapidly with hydrochloric 
acid, it is converted into isatin, while chromic acid oxidizes it to 
acetorthamidobenzoic acid, the first product being probably 
acetanthranil (Part IV., p. 240), which then combines with 
water :” 


CO CO 


431 Ovex, Hidea| + 60s 
"\-N Z.00.CH, * \N.CO.CH, : 
Go : CO.0OH 
CHK | + H,O = Cras aa 
N.CO.CH, N<Go on, 


1 Antrick, Ann. Chem. Pharm. cexxvii. 864. 
2 vy, Meyer and Bellmann, Journ. Prakt, Chem, [2], xxxiii. 31. 


86 AROMATIC COMPOUNDS. 


Acetylisatic acid, C,H,(NH.CO.CH,)CO.CO,H, is obtained by 
the addition of dilute sulphuric acid to a solution of acetyl- 
pseudo-isatin in cold, dilute caustic soda, as a yellow crystalline 
powder, which crystallizes from alcohol in colourless needles, 
melting at 160°, and is converted into isatin by boiling hydro- 
chloric acid! Sodium amalgam reduces it in acetic acid 
solution to acetylhydridinic acid (p. 54). 

Acetylisatic acid is more stable than isatic acid, while ethy]- 
isatic acid is not known in the free state. The stability of 
isatic acid is therefore mcreased when the hydrogen of the 
amido-group is replaced by an acid radical, but is diminished 
by the introduction of an ethyl group (Baeyer). 

Acetylbromopseudo-isatin, C,H,BrO,NCO.CH,, is formed by 
boiling bromisatin with acetic anhydride for some time and 
crystallizes from benzene in straw-yellow prisms, melting at 
170°—172°. 

Acetylbromisatic acid, C,H,(NH.CO.CH,)CO.CO,H, is obtained 
by the addition of an acid to a solution of acetylbromopseudo-isatin ; 
it separates out in fascicular groups of colourless needles, which 
melt at 178°—180° with evolution of gas. The acetyl group in 
this compound is more firmly combined than in acetylisatic acid, 
since it does not, like the latter, give the indophenin reaction 
with benzene and sulphuric acid in presence of thiophene.? 

2318 Tolu-isatin, C,,H,,NO. Pure benzene does not react 
with isatin and sulphuric acid, whereas toluene immediately 
enters into combination when it is shaken up with a solution 
of isatin in sulphuric acid, the red colour changing to greenish- 
brown and toluisatin being formed. It crystallizes from alcohol in 
colourless, lustrous needles, which melt at 200°—201°, and are 
insoluble in caustic potash even on boiling, but dissolve in fused 
caustic potash without decomposition. 

Ethyltolu-isatin, Cy.H4.(C,H;)NO, is obtamed by heating 
tolu-isatin with ethyl iodide and sodium ethylate and crystallizes 
from ether in small plates, which melt at 108° and are not 
attacked by boiling alcoholic potash or by heating with hydro- 
chloric acid. The same compound is formed when ethyl- 
pseudo-isatin is shaken up with toluene and sulphuric acid, as 
wellas when ethyltolindolcarboxylic acid is oxidized with sodium 
hypochlorite. 


1 Suida, Ber. Deutsch. Chem. Ges. xi. 584. 
2 Baeyer, zbid. xv. 2096. 
3 Hegel, Ann. Chem. Pharm, xxxii. 219. 


IMESATIN. oF 87 





Tolu-isatin is therefore a derivative of pseudo-isatin and is 
formed in the followmg manner: 
Js issACIels 
——C, H, CH, 


HK © S00 + 20,H,CH, = = OH 0b * aaa 


It may therefore be termed ditolyloxindol. 

Phenolisatin, C,j5H,;NO3, is formed when sulphuric acid is 
added to a solution of isatin in phenol and crystallizes from 
chloroform in fine, white needles, which melt at 220°, are readily 
soluble in alkalis and are reprecipitated by acids. It probably 
has the following constitution : 

Je H,OH 
ae a H, OH 
AK 00” 
NH 


Tsatin not only condenses with hydrocarbons and phenols, but 
also with tertiary bases (Baeyer and Lazarus). 

2319 Jmesatin, C,H,N,O, is formed by the action of ammonia 
on ree ; 


OOH + NH, Do 94 “SCOH + 10. 


KX *‘\nZ 


Tn order to obtain it, ammonia is passed into warm ether in which 
isatin is suspended, It crystallizes on evaporation in odourless, 
dark yellow, rectangular prisms and is converted into isatin by 
heating with alkalis or acids (Laurent). 

Laurent obtained other complex substances by the action of 
ammonia on isatin in presence of alcohol. 

Isatindiamide, C,,H,,.N,0,, is the name given by Sommaruga 
to a substance, which is formed among others when isatin is 
heated to 100° with alcoholic ammonia. It crystallizes in light 
yellow, matted needles, which are insoluble in water and only 
dissolve slightly in alcohol. 

Lsatindiamide hydrochloride, C,,H,,.N,O,.HCI, forms a yellow, 
crystalline powder, which is scarcely soluble in cold, only 
slightly in hot water and loses hydrochloric acid when boiled 
with water. 

Lsatindiamide sulphate, C,,H,,N ,O0,.50,H,, crystallizes in light 


1 Baeyer and Lazarus, Ber. Deutsch. Chem. Ges, xviii. 2638, 
272 


88 AROMATIC COMPOUNDS. 





yellow needles, which form groups resembling “ crabs’ eyes” 
(lapis cancrorum). 

Monamido-isatin, C,gH,,N,05, is formed by boiling the diamide 
with caustic potash and crystallizes from alcohol in small, 
yellowish needles, which are readily soluble in alkalis, with 
which they combine. 

Oxydimidodiamido-isatin, C,,H,,N,O3, is obtained together 
with the diamide and crystallizes from hot water or alcohol in 
needles, which taste sweet and then acrid. It combines with 
acids to form salts, which are crystalline and yield solutions which 
exhibit a splendid, bluish-red fluorescence.’ 

Phenylhydrazine-imesatin is formed when an aqueous solu- 
tion of isatin and phenylhydrazine hydrochloride is heated to 
boiling : 


== C.0H Ne C0. 0H: 
| | ae N,H;.C,H, =F | | 26 H,0. 
C,H,—CO C,H,—C=N,H.C,H, 


It crystallizes from boiling alcohol in fine, yellowish-red needles, 
melting at 210°—211°. A solution of one part of isatin in 
2,000 parts of water gives a precipitate of this compound after 
a few moments, and even when the solution is only one-tenth of 
this stréngth the fine needles can be detected.” 

Phenylimesatin, C,H,(C,H;)N,O, is prepared by heating aniline 
with isatin and a little absolute alcohol : ® 


CEN. 
OK "oon + NH, C,H, =CHC > \C.OH ” + H,0. 


It is also formed when aniline is heated with dichloracetic 
acid.4 

Phenylimesatin crystallizes from alcohol in stellate groups of 
yellow, pointed prisms and is decomposed into isatin and aniline 
by heating with alkalis and hydrochloric acid. 

If the homologues of aniline be employed in this reaction, 
homologous imesatins and isatins are formed, the best known of 
which is that prepared from paratoluidine, which will therefore 

is Sommaruga, Ann. Chem. Pharm. exe. 367; exciv. 85; Monatsh. Chem. i. 
hee Fischer, Ber. Deutsch. Chem. Ges. XVil. 577. 


3 Engelhardt, Journ. Prakt. Chem. [1], xix. 358. 


4p. Meyer, Ber, Deutsch. Chem. Ges. xvi. 2942 ; see also the two following 
references. 


PARATOLYLPARAMETHYLAMIDOXINDOL. 89 


be described here, although it belongs to the group of compounds 
with nine atoms of carbon. 

Paratolylparamethylimesatin, C,,H,,N,O, was prepared by 
P. J. Meyer by heating paratoluidine with dichloracetic acid." 
Dibromacetic acid may also be employed in its preparation. 

Paratolylparamethylamidoxindol, is the first product of the 
reaction : 

CHCl, 
2CH,.C,H,NH, + | = 
CO'OH 
CH_NH(C,H,.CHs) 
Oras S Pa + 2HCl + H,O. 
NH 


This substance crystallizes from hot alcohol in small, white 
needles and forms a solution which has a persistent, biting taste, 
rapidly absorbs oxygen from the air and is oxidized by an 
ammoniacal silver solution, the imesatin being formed and a 
splendid silver-mirror deposited :? 


OHNE (CoH, CH,) 
CH, OH >CO +0= 
NH 


/PRNO HCH, 
CH, CHC DO. + H,0. 


It is insoluble in water and crystallizes from hot alcohol in 
golden-yellow, lustrous needles or plates, which melt at 259° to 
a dark red liquid. When treated with concentrated caustic soda 
solution, it forms a salt, which crystallizes in red prisms and is 
decomposed by water. 

Lthyltolylparamethylimesatin, C,,H,;(C,H;)N,O, is obtained 
by heating the imesatin with ethyl bromide and a solution of 
sodium ethylate. It crystallizes in large, orange-red prisms, 
which fuse at 151°—152° to a blood-red liquid. 

Acetyltolylparamethylimesatin, C,,H,.(C,H,0)N,O, is formed 
when the imesatin is heated with acetic anhydride and crystal- 
lizes from alcohol in small, deep .red, lustrous needles, fusing 
at 121°—122° to a blood-red liquid, which solidifies to a vitreous 
mass. 

Paramethylimesatin, C5H,(CH,)NO.NH, is obtained by heat- 
ing tolylmethylimesatin with alcoholic ammonia and crystallizes 


1 Ber. Deutsch. Chem. Ges, xvi, 2261. 2 Duisberg, zbid. xviii. 190. 


90 AROMATIC COMPOUNDS. 





from a large amount of hot water in fine, soft needles, which dry 
to a silver-lustrous mass resembling paper. It shows no similarity 
to Laurent’s imesatin and is probably homologous with isatin- 
diamide. 

2320 Paramethylisatin, C,5H,(CH;)NO,, is prepared by the 
action of hydrochloric acid on tolylmethylimesatin and separates 
from alcohol in large, deep red, transparent crystals, while it 
crystallizes from water in lustrous, red plates, melting at 187’. 
It dissolves in alkalis, forming a. deep violet-coloured solution, 
which changes to yellow on standing or heating, a paramethyl- 
isatate being formed, which yields the original paramethylisatin 
on decomposition with acids. 

This compound is homologous with isatin and metameric with 
its methyl ether. 

On heating with alcohol and paratoluidine the original 
compound is again formed : 


CO 
OH OHC _DO.OH + HLN.GH, CHa 


C=N.C,H,.CH, 


CH.C,H< \C.OH. 


*\nZ 


It is therefore a lactim, and not a lactam, as its formation 
from dichloracetic acid would seem to show. The fact that 
it forms alkali salts is also in favour of this conclusion. 

Phenylparamethylimesatin, C,H,(NC,H;)NO, has been pre- 
pared from paramethylisatin and aniline, and crystallizes in 
thick, yellowish-red tablets or prisms, melting at 239°—240°. 

Phenylhydrazineparamethylimesatin, C,H,(N,H.C,H,)N0, crys- 
tallizes from hot alcohol in golden-yellow needles, which sublime 
at 240° and only melt at 300°, decomposition accompanied by 
evolution of gas taking place. 

Lthylparamethylpseudo-isatin or LHthylpseudoparatolisatin, 
‘C,H,O,(NC,H,), is formed by the action of cold, concentrated 
hydrochloric acid on ethyltolylparamethylimesatin, and also by 
the oxidation of ethylparatolindol with sodium hypochlorite.” 
It crystallizes from hot water or petroleum-spirit in blood-red 
needles or prisms, melting at 109°—110°, and forms a yellow 
solution in alkalis. It resembles ethylpseudo-isatin in its behaviour 


1 Panaotovic, Journ. Prakt. Chem. [2], xxxiii. 73. 
* Hegel, Ann. Chem. Pharm. ccexxxii, 214. 


ISATOXIME. 91 


towards reducing agents, yielding a yellow substance, but no 
colouring-matter of the indigo group. 
The following compounds have been prepared by Hegel from 
the corresponding indols : 
Melting-point. 
Methylpseudoparatolisatin, red needles . . 148° 
Methylpseudorthotolisatin, brick-red needles 157° 


Acetylparamethylpseudo-isatin, C,H,O,(NC,H,0), is obtained 
by the decomposition of acetyltolylmethylimesatin by means of 
hydrochloric acid, as well as by boiling paramethylisatin with 
acetic anhydride. It crystallizes from benzene in lemon-yellow 
needles, which melt at 172° and dissolve in caustic soda solution. 
On the addition of hydrochloric acid to this solution, acetylpara- 
methylisatic acid, C,H,(CH,)(NH.CO.CH,)CO.CO,H, is precipi- 
tated ; it crystallizes from hot water in small, white needles, 
which melt with decomposition at 172° (Duisberg). 

2321 Isatinoxime or IJsatoxime, C,H,N,O,, was prepared by 
Baeyer and Knop, who named it nztrosowindol+ (p. 74), by 
passing nitrogen trioxide into a 1 per cent. aqueous solution of 
oxindol. It is also formed when hydroxylamine and isatin are 
brought together in solution in dilute alcohol: * 


C=N.0OH 
0H + H,NOH - CHS SC.0H EG 
NZ 


peas 
Tee 
In its formation from eaindol, the first product is probably 


isonitroso-oxindol, which immediately undergoes intermolecular 
change plane to pseudo-isatin : 


//O=NOH 
SO + ONOH =C Bice 40 

WK > = 2 ONT “ 1 

C—N.OH ox NOH 

G, HC > S00 = GHC Ce OH 


Isatoxime crystallizes in very fine, long, golden-yellow needles, 
which are very slightly soluble in water, more readily in alcohol, 
and melt at about 202° with decomposition. It forms a dark 
reddish brown coloured solution in alkalis, from which it is 
reprecipitated by acids. 


1 Ann. Chem. Pharm. cx. 34. 2 Ber. Deutsch. Chem. Ges. xvi. 517. 


92 AROMATIC COMPOUNDS. 


Silver isatoximate, C,H,N,O,Ag, is formed when ammonia is 
added to an alcoholic solution of silver nitrate and isatoxime, 
as an orange-coloured, gelatinous precipitate, which dries to a 
brick-red Hower 

Ethyl isatoximate or Isato-ethylowime, C,H,N,O,(C,H;), 
readily formed by the action of ethyl iodide on the silver salt, 
crystallizes from alcohol in fine, yellow needles, melting at 188", 
and dissolves in caustic soda, forming a solution from which 

it is precipitated by carbon dioxide. 

——- Stlver ethyl isatoximate, C,5H,N,0,Ag(C,H,), is prepared in a 
similar manner to silver isatoximate, and is an amorphous 
brick-red powder. 

Diethyl isatoximate or Ethylisato- ethyloxime, C,H,N,O,(C,H;)., 
is obtained when the preceding compound is biped to stand 
for some time in contact with an ethereal solution of ethyl iodide. 
It remains after the evaporation of the ether as a light yellow 
oil, which solidifies at the ordinary winter temperature and 
rapidly changes to a viscid, yellowish-red mass. It dissolves 
with difficulty in cold caustic soda solution and is converted 
into isato-ethyloxime by it on boiling. Since the ethers of the 
oximes are stable substances, while those of isatin are very 
unstable, the constitution .of these two ethyl ethers must be 
as follows:! 


C=N.OC,H, C-—N.OU,H- 


Wee He! 
HKD \C.OH AK $0.06, 


Isato- eee Etat he yloxime. 


2322 Amidoxindol, C;H,N,O, is formed by the reduction of 
isatoxime with tin and hydrochloric acid. Its hydrochloride, 
C.H,N,O,HCI, forms colourless warty masses and is decomposed 
by water with separation of a red resinous substance. It is 
quantitatively converted into isatin by the action of ferric 
chloride, cupric chloride or nitrous acid.? Its constitution. is 
probably expressed by one of the following formule : 


pole NH, CHS Aa 


ney, 
AK Door aoe 


The ethers of isatoxime are also converted into isatin by 
reduction and subsequent oxidation. 


1 Baeyer and Comstock, Ber, Deutsch. Chem. Ges. xvi. 1704. 
2 Baeyer, ibid. xi. 1228, 


DERIVATIVES OF ISATOXIME. 93 





Bromisatoxime, C,H,BrN,0,, is obtained by the addition of 
bromine water to a cold solution of isatoxime in the form of light 
yellow, lustrous needles, which are very slightly soluble in water, 
more readily in alcohol, and decompose at 240° without melting. 
It dissolves in caustic potash solution and is reprecipitated by 
acids (Baeyer and Knop). 

Dibromisatoxime, C,H,Br,N,O,, is formed by the combination 
of hydroxylamine with dibromisatin; it is slightly soluble in 
alcohol and crystallizes from glacial acetic acid in thick, light- 
yellow, pointed needles, which carbonize at about 255°. 

Dibromisato-ethyloxime, C,H,Br,N,0,(C,H,), is prepared from 
the red silver salt of the preceding compound and ethyl iodide. 
It crystallizes from acetone in long, yellow, silky needles, melting 
at 115°—116°. It is converted into dibromisatin by successive 
reduction and oxidation (Baeyer and Comstock). 

Tribromisatoxime, C,H, Br,N,0,, is formed when an aqueous 
solution of isatoxime is heated with an excess of bromine. It is 
insoluble in water and crystallizes from boiling alcohol in dirty 
violet needles, which melt at 162° and commence to sublime in 
red prismatic needles at 190° (Baeyer and Knop). 

Diazo-isatoxime chloride, C,H,N,O,Cl, is obtained by adding 
amyl] nitrite to an alcoholic solution of paramido-oxindol (p. 22) 
acidified with hydrochloric acid : 


AE, 
2NO.OH + HCl+H,N.C,H, SCO = 


| be oN OH 
CIN=NC,HiC >CO + 3H,0. 
NH 


It separates in golden-yellow needles, which explode on heat- 
ing, and is converted into isatoxime by boiling with alcoholic 
hydrochloric acid.t 

Paramethylisatoxime, C,H,N,O0,, is formed by the action of 
hydroxylamine on paramethylisatin (p. 90) and crystallizes in 
long yellow prisms, melting at 225°—226°? 

2323 Pseudo-isatin-a-oxime, C,H,N,O,, which was formerly 
known as nitroso-indoxyl (p. 40), is prepared by the action of 
nitrous acid on ethylindoxylic acid. This assumes the elements 
of water and is then converted with elimination of alcohol and 

1 Gabriel and Meyer, Ber. Deutsch. Chem. Ges, xiv. 832, and 2332 ; Gabriel, 


ibid. xvi. 517. 
2 Pp. J. Meyer, bid. xvi. 2261. 


94 AROMATIC COMPOUNDS. 


———— 


carbon dioxide into pseudo-indoxyl, which is then acted upon 
by the nitrous acid (Baeyer) : 


CH, 
HX _So= 06,8 + 1,0 = 


ae 
ot + HO.C,H, + CO,, 


CO 
OH >On, + ON.OH = st Ae "Sean N.OH+H,0. 


It crystallizes from alcohol in strongly lustrous, yellow or 
orange-coloured needles, which decompose at about 200° without 
melting at any definite temperature. It is converted into isatin 
by reduction and subsequent oxidation, while ammonium sulphide 
reduces it to indigo-blue. 

Pseudo-isatin-a-ethyloxime, C,5H;N,0,(C,H;), is formed when 
the preceding compound is treated with sodium ethylate and 
ethyl iodide. It crystallizes in brownish-yellow plates, melting 
at 135°, dissolves in alcoholic potash with a violet and in alcoholic 
sodium ethylate with a blue colour. It can be converted into 
isatin and indigo-blue in the same way as pseudo-isatin-a- 
oxime.! 

Ethylpseudo-isatin-a-ethyloxime, C,H,N,O0,(C,H,),, is obtained 
by the further action of sodium ethylate and ethyl iodide on the 
preceding compound : 


CO 
CHK > —NOG;H, +,0,H.5 = 


CO 
CHC . C=NOC.H, + HL 


C.H, 


It crystallizes from hot water in yellow needles, which melt at 
99° and sublime at a higher temperature. It is converted into 
diethylindigo by the action of ammonium sulphide : 2 


1 Baeyer, Ber. Deutsch. Chem. Ges. xv. 782; xvi. 2191. 
2 Ibid, xvi. 2201. 


ISATYDE. 95 





20K " o=NocaH, res Ee 
, 


Cite 
cH’ AP IN 
RX Dea DO + 2NH, + 2C,H,.OH. 
i | 
CoH; OP a i 


Ethylpseudo-isatin-8-oxime, C,H,0,.N,C,H,, is the product of 
the combination of ethylpseudo-isatin with hydroxylamine : 


CO C—N.OH 

CHK x co + H,N.OH = CHK $008.11 4:50. 
| | 
C,H, C,H, 


It crystallizes from alcohol in yellow, four-sided prisms, melting 
at 160°—162°, does not yield an indigo colour when treated with 
ammonium sulphide and is converted into ethylpseudo-isatin by 
reduction followed by oxidation.! 

2324 Isatyde, C,,H,,N,O,, was prepared by Erdmann by dis- 
solving isatin in warm ammonium sulphide? while Laurent 
obtained it by the action of the same reagent on an alcoholic 
solution of isatin.? He subsequently found that it is also formed 
when isatin is gently warmed with zinc and very dilute sulphuric 
acid. The yellowish-red solution of isatin in glacial acetic acid 
is decolourized by zine dust in the cold, but becomes coloured 
again on exposure to the air, while dioxindol is formed when its 
aqueous solution is boiled with zinc dust and a little hydrochloric 
acid, isatyde being however produced if the solution contain 
isatin in suspension (Baeyer). The latter substance is best 
prepared by boiling isatin with glacial acetic acid and zinc dust.® 
It is also formed when an aqueous solution of dioxindol is 
exposed to the air (Baeyer and Knop). It is a white, yellowish 
or reddish powder, which is almost insoluble in water and only 


1 Ber. Deutsch. Chem. Ges. xvi. 2196. 

2 Journ. Prakt. Chem. xxiv. 15. 

3 Ibid. xxv. 486; Ann. Chim. Phys. [3], iii. 382. 
4 Ann. Chem. Pharm. )xxii. 285. 

5 Ber. Deutsch. Chem. Ges. xii. 1309. 


96 AROMATIC COMPOUNDS. 


slightly soluble in alcohol, from which it crystallizes m oblique 
microscopic prisms. 

The substitution products of isatyde are formed by the reduction 
of the corresponding derivatives of isatin with ammonium sulphide. 

Dithio-isatyde, C,,H,,N,0.5,, termed sulphisatin by Erdmann 
and sulphisathyde by Laurent, is formed when sulphuretted 
hydrogen is passed into a boiling alcoholic solution of isatin, and 
forms a yellowish-grey powder, which is insoluble in water, but 
readily soluble in alcohol. 

Thio-isatyde, C,,H,,N,O,8, was prepared by Laurent, who 
named it sulphasathyde, by gradually adding caustic potash to an 
alcoholic solution of dithio-isatyde. It is a colourless crystalline 
powder, which is insoluble in water and only slightly soluble in 
alcohol. | 

Isatyde may be considered from its method of formation to be 
the pinacone of isatin or more probably of pseudo-isatin, and the 
constitution of the preceding compounds can then be expressed 
by the following formule : 


‘aa Thio- ek Dithio- se de. 
on Yoo *"\co co 
RN oZon Con rte CHK _“SH 
ie | | 
Oe ae 


HK at ‘\NE ines 


Indin, C,,H,,N,O,, is formed when the compounds just 
described are boiled with alcoholic potash, isatic acid being also 
obtained when isatyde is employed. A simultaneous reduction 
and oxidation therefore take place : 


NH 
C Mei, “co eee <eie 
DOS OT C275 


2 | + 2KOH = I 
"Sco > 
AK oy AK 
a 
+ 20,H, + 2H,0. 
\NH, 


Indin is isomeric with indigo-blue and forms dark rose- 
coloured, microscopic crystals, which are insoluble in water and 


ISATOIC ACID. 97 





only slightly soluble in alcohol. Knop obtained an isomeric, or 
possibly identical substance, as a violet-red amorphous powder 
by heating dioxindol with glycerol. When indin is treated with 
concentrated alcoholic potash, it yields the potassium salt of 
indie acid, C,,H,,N,0,K, which forms small black crystals, which 
are decomposed by water with formation of the original indin 
(Laurent). 

Laurent and Knop have prepared other reduction products of 
isatin in addition to those already described, and Schiitzenberger 
has also obtained compounds of complex composition by heating 
isatin with hydriodic acid. 

2325. Isatoie acid, C,H,NO,, was first prepared by Kolbe by 
the oxidation of isatin with a solution of chromium trioxide in 
glacial acetic acid. He found that it crystallizes from acetone in 
hard, yellow prisms, is decomposed into orthamidobenzoic acid 
and carbon dioxide when boiled with water or heated with 
bases or acids, and determined other of its properties. This was 
his last research? and was continued by E. v. Meyer and his 
pupils. This chemist noticed the great similarity existing 
between this acid and anthranilearboxylic acid (Part IV. 
p. 240), from which it differs in its yellow colour and greater 
instability. These differences were afterwards shown to be due 
to an admixed substance, which can be removed by means of 
nitrous acids or other oxidizing agents, the purified compound 
being identical with anthtanilcarboxylic acid* It is formed 
from isatin according to the following equation : 


Ste. CO 
Pa \o OH ys 
Heo G.H<.| 
\n 4 **\N.C0.0H. 


It is obtained from anthranil, as already mentioned, by heat- 
ing with ethyl chlorocarbonic acid to 120°—140°° It crystal- 
lizes from hot water in white needles, or when impure in 
yellow prisms, which melt at 230° and decompose into anthra- 
nil and carbon dioxide, while it changes into anthranilic acid 
when dissolved in alkalis or heated with strong hydrochloric acid. 

Substitution products of isatorve acid. One atom of hydrogen in 
this acid can be replaced by the action of chlorine or bromine, 


C,H, 


1 Bull. Soc. Chim. 1865, 170. 

2 Journ. Prakt. Chem, [2], xxx, 467. 

3 Ibid. [2], xxx. 454. 

4 Meyer and Bellmann, zbid. [2], xxxiii. 18. 

> Friedlander and Wleiigel, Ber. Dewtsch. Chem. Ges. xvi. 2227. 


98 AROMATIC COMPOUNDS. 


i 


while derivations of anthranilic acid are formed on further 
treatment. The substituted isatoic acids can however be easily 
obtained by the oxidation of the corresponding isatin derivatives 
with a solution of chromium trioxide in glacial acetic acid ; they 
form sandy, crystalline powders and can be crystallized from a 
mixture of alcohol and acetone * 

Chlorisatoic acid, C,H,CIN O,, forms long, rectangular, nacreous 
plates, which fuse at 265°—268° with decomposition accompanied 
by frothing. On boiling with hydrochloric acids it yields a 
chlororthamidobenzoic acid, which crystallizes from alcohol in long 
needles, melting at 204°. The chlorine atom in this compound 
must be in the para-position to the amido-group, since chlorisatin 
yields parachloraniline on heating with caustic potash. This 
constitution however has been ascribed to 6-chlororthamidoben- 
zoic acid, melting at 148° (Pt. IV. p. 25), which is converted by the 
diazo-reaction into the chlorosalicylic acid, which is prepared from 
parachlorophenol and tetrachloromethane. The question as to the 
actual constitutions of these bodies is therefore still an open one. 

Dichlorisatoic acid, C;H,C1,NOx,, crystallizes in yellow prisms, 
apparently belonging to the rhombic system, which melt with 
decomposition at 254°—256°. It is only converted into dichloro- 
orthamidobenzoic acid by long continued boiling with con- 
centrated hydrochloric acid; this substance melts at 222°—224", 
and crystallizes in small needles. 

Bromisatoic acid, C,H,BrNO,, crystallizes in white, nacreous 
plates, which melt with decomposition at 270°—275°, and are 
converted into $-bromamidobenzoic acid by boiling with 
hydrochloric acid. 

Dibromisatoie acid, C,5H,Br,N O,, forms flesh-coloured groups of 
prisms, melting at 255°, and is converted into parametadibromo- 
orthamidobenzoic acid by continued boiling with hydrochloric 
acid. In the bromination of isatin, therefore, the second bromine 
atom takes the meta-position to the nitrogen atom and not the 
ortho-position, as stated by Baeyer (p. 80). 

Nitro-isatore acid, C,H,(NO,)NO,, is readily formed by the 
action of concentrated nitric acid on isatoic acid, and crystallizes 
from a mixture of acetone and alcohol in colourless, nacreous 
plates, which melt with decomposition between 220°—230°. On 
evaporation with hydrochloric acid, e-nitro-amidobenzoiec acid is 
formed, while it is reduced by tin and hydrochloric acid to 
a-diamidobenzoic acid (Pt. IV. p. 258).2 The nitroxyl group is 

1 Dorsch, Journ. Prakt. Chem. [2], xxxiii. 32. 2 Kolbe, ibid. [2], xxx. 477. 


ANTHROXANALDEHYDE. 99 


therefore situated in the para-position with respect to the 
nitrogen atom, 

Paramethylisatore acid, C,AH,NO3, is formed by the oxidation 
of paramethylisatin with chromic acid : 


CO CO 
CH.  NUOH POSCMONS ) 
ay SN “"*"\N.CO.OH. 


It is slightly soluble in water, more readily in boiling alcohol, 
ether and benzene, and very readily in acetone, from which it 
crystallizes in small, rhombic prisms. It decomposes suddenly 
at 245°, with formation of a voluminous mass, which melts above 
300° with evolution of carbon dioxide. It is not decomposed 
by boiling water or dilute acids, but on heating with concentrated 
hydrochloric acid, it is resolved into carbon dioxide and a-amido- 
metatoluic acid, which is converted into parahomosalicylic acid 
by the diazo-reaction. 

Nitroparamethylisatoic acid, Cy5xH,(NO,)NO,, crystallizes from 
benzene in light yellow, rhombic tablets, melting at 175°, and is 
converted into diamidotoluic acid by reduction! 

Anthroxanaldehyde, C,H;NO,, is isomeric with isatin and is 
formed, together with anthranil, when orthonitrophenylhydroxy- 
acrylic acid, C,H,(NO,)C,H(OH)CO,H, is distilled with steam. 
It crystallizes from hot water or petroleum-spirit in long 
yellowish needles, melting at 72°5°, has a penetrating aromatic 
odour and yields a vapour which causes violent sneezing. Its 
solution in very dilute aqueous ammonia becomes coloured an 
intense violet-red when gently warmed with zinc dust. It 
dissolves readily in a concentrated solution of acid sodium 
sulphite, and, like other aldehydes, restores the colour to a solu- 
tion of fuchsin which has been decolourized by sulphurous acid. 

Anthroxame acid, C,H,NO;, which is metameric with isatoic 
acid, is formed by the oxidation of its aldehyde with alkaline 
permanganate. It is scarcely soluble in cold, but more readily 
in hot water, from which it crystallizes in fine white needles, 
melting at 190°—191°. It is converted into isatic acid by 
reduction with ferrous sulphate in ammoniacal solution : ” 


C—CO.0H CO—CO.OH 
CHK { pe + 2H = CHK oy 
2 


1 Panaotovii, Jowrn. Prakt. Chem. [2], xxxiil. 57. 
2 Schillinger and Wleiigel, Ber. Dewtsch. Chem. Ges. xvi. 2222. 


100 AROMATIC COMPOUNDS. | 





ETHENYLBENZENE OR PHENYLACETYLENE. 


2326 Glaser first prepared this hydrocarbon from phenyl- 
propiolic acid, C,H;.C = C.CO,H, by heating it with water to 
120°, or submitting its barium salt to dry distillation. He then 
found that it is also formed when #$-phenylbromethylene, 
C,H;.CBr—CH,, is heated with alcoholic potash to 120° and 
Friedel prepared it in a similar manner from $-phenylchlor- 
ethylene.?, According to Morgan, a much better yield is obtained 
when the latter compound, or the product of the action of 
phosphorus pentachloride on acetophenone, is passed over soda- 
lime heated to incipient redness.® 

Phenylacetylene is a liquid, which has a characteristic, pleasant 
odour, boils at 139°—140° and combines with water to form 
acetopbenone, C,H;.CO.CH,, when it isshaken up with tolerably 
dilute sulphuric acid. It forms metallic compounds, which 
correspond to those of acetylene (Glaser). 

Sodium phenylacetylene, C,H;.C,Na, 1s formed by the action of 
sodium on an ethereal solution of the hydrocarbon and is a 
white powder, which ignites in the air and combines directly 
with carbon dioxide to form sodium phenylpropiolate. 

Silver phenylacetylene, C,H,;.C,Ag + Ag,O, is obtained as a 
gelatinous precipitate when an alcoholic solution of the hydro- 
carbon is treated with ammoniacal silver solution. After drying 
it forms a light grey powder, which detonates on heating. 

Cuprous phenylacetylene, (C,H;.C,),Cu,, is prepared in a similar 
manner, an ammoniacal cuprous chloride solution being em- 
ployed, and is a light yellow precipitate, which, on agitation 
with alcoholic ammonia in presence of air, is convertéd into 
diphenyldiacetylene, C,H;.C = C —C =C,H,, which is the 
mother-substance of indigo and will be subsequently described. 

Orthonitrophenylacetylene, C,H,(NO,)C,H, is formed when 
orthonitropropiolic acid is heated with water, and crystallizes 
from dilute alcohol in needles, melting at 81°—82°, has a 
pungent odour and gives a yellowish white silver compound 


1 Ann. Chem. Pharm. cliv. 151. 

2 Compt. Rend. \xvii. 1192. 

3 Journ. Chem. Soc. 1876, i. 164. 

4 Friedel and Balsohn, Bull. Soc. Chim. xxxv. 565. 


PARANITROPHENYLACETYLENE. _ 101 





and a red copper compound! On treatment with zinc dust and 
ammonia, orthamidophenylacetylene, C,H,(NH,)C,H, is formed 
as a thick, yellow, oily liquid, which has a characteristic odour 
similar to that of naphthalene; in the dilute state however its 
vapour has a smell resembling that of an indigo-vat,’ or, according 
to Miiller, that of jasmine. 

Paranitrophenylacetylene is obtained by heating paranitro- 
phenylpropiolic acid with water, crystallizes in long needles, 
melting at 152°, and has an odour resembling that of cinnamon, 
while that of its ethereal solution is unpleasant and pungent. 
It forms a yellow silver compound and a red copper compound.* 

1 Baeyer, Ber. Deutsch. Chem. Ges. xiii. 2259. 


2 Baeyer and Landsberg, zbid. xv. 60. 
3 Miller, Ann. Chem. Pharm. ccxii. 133 and 139 ; Drewsen, zbid. ccxii. 158. 


102 AROMATIC COMPOUNDS. 





CUMENE GROUP. 


2327 In the year 1838 Pelletier and Walter examined the 
oil, which is obtained as a by-product in the manufacture of 
illuminating gas from pine resin, and found in it both retin- 
naphtha (toluene) and a substance boiling at 150°, which they 
named retinnyl,| C,H,,. In the same year Robert Kane ob- 
tained an isomeride of this, mesztylene, by the distillation of 
acetone, and gave to it the formula C,H,, since he believed that 
it bore the same relation to acetone, C,H,O, which he termed 
mesitic alcohol, as ethylene to ethyl alcohol? Cahours and 
Gerhardt soon afterwards discovered that cumol, C,H,,, a liquid 
boiling at 144°, is formed by the distillation of cuminic acid 
with baryta, and that the compound of this with sulphuric acid 
yields a barium salt differing from the corresponding retinnyl 
derivative? About the same time they discovered in Roman 
cumin oil a compound, cymol, C,,H,,, which boils at 175°. 
Mansfield, as already mentioned (Pt. IV. p. 386), believed 
that he had also detected those two hydrocarbons in coal tar. 

A more complete investigation of mesitylene, which was 
conducted by Hofmann, proved that it also has the molecular 
formula C,H,,, but is quite distinct from the cumol prepared 
from cumic acid. Cahours, who ascertained the presence of the- 
latter hydrocarbon and its homologues in crude wood-spirit, made 


1 Ann. Chim. Phys. xvii. 285; Pogg. Ann. xliv. 81. 

2 Ibid. xliv. 473. Reichenbach gave to acetone, or spirit of vinegar, which he 
found among the distillation products of wood, the name of mesit (uecirns, the 
mediator) : ‘‘ Spirit of vinegar may be regarded as standing, to a certain extent, 
between alcohol and ether ; according to my observations it especially occupies 
the position of a mediator among the empyreumatic substances, since it unites 
many of these, which are either insoluble or only slightly soluble in one another, 
in a common whole, like tar or wood-vinegar” (Schweigg, Journ. Chem. Phys. 
xix. 175. 

3 Ann. Chem. Pharm, xxxviii. 95. 

4 Ibid. 1xxi. 121; Cahours, ibid. Ixxiv. 106. 


HISTORY OF THE CUMENE GROUP, 103 





the important observation that the fraction boiling at 164°— 
168° has also the same composition and vapour density as 
cumol and mesitylene, but differs from both of these in its 
properties. 

In a short communication on the hydrocarbons of the benzene 
series, Warren de la Rue and Miiller stated that the coal tar 
naphtha employed by them consisted chiefly of toluol, xylol 
and pseudocumoel,? while Fritzsche found that the cumol extracted 
from tar yields.a sulphuric acid derivative, the barium salt 
of which seems to agree in its properties with that of retin- 
nylsulphuric acid.* 

As it was then found that the fraction of coal-tar which boils 
at about 140° is not cumol but xylol, it appeared very probable 
that Mansfield’s cymol would prove to be the next higher 
homologue of this, and therefore isomeric with the cumol 
from cumic acid, and this was soon experimentally established, 
the substance being therefore named isoewmol,* cumol from coal 
tar, or pseudocumol.® 

It was afterwards proved by a more complete investigation 
that itis a mixture of mesitylene with another trimethylbenzene, 
for which the name of pseudocumol was retained,’ and Jacobsen 
subsequently showed that the third trimethylbenzene is also 
present.® 

The following hydrocarbons of the formula C,H,, are now 
known : 


s-Trimethylbenzene or Mesitylene 
a-Trimethylbenzene or Pseudocumene loan, 
v-Trimethylbenzene or Hemellithene 
Paramethylethylbenzene CH, 
Metamethylethylbenzene hoa : 
Orthomethylethylbenzene C,H, 
Isopropylbenzene or Cumene, C,H,;.CH(CH,), 
Propylbenzene, C,H,.C,H.. 


1 Ann. Chem. Pharm, 1xxvi. 286. 

2 Ibid. cxx. 339. 

3 Jahresb. Chem. 1862, 420. 

4 C. M. Warren, Jahresber. Chem. 1865, 514, 

5 Beilstein and Kogler, Ann. Chem. Pharm. cxxxyii. 317. 
6 Fittig, ibid. exlv. 138. 

7 Fittig and Wackenroder, ibid. cli. 292. 

8 Ber. Deutsch. Chem. Ges. xix. 2511. 


273 


104 AROMATIC COMPOUNDS. 





THE TRIMETHYLBENZENES C uCon 


2328 s-Trimethylbenzene or Mesitylene is formed by e 
acetone, C,H,O, mesitoxide, C,H,,O, or phoron,t C)H,,O (Pt. I. 
p. 578), with sulphuric acid, as well as when allylene is dissolved 
in sulphuric acid and the allylenesulphonic acid which is formed 
distilled with water :? 


3CH,.C,S0,H + 3H,O = (CH,),C,H, + 3S0,H,. 


When methyl chloride is allowed to act upon metaxylene in 
presence of aluminium chloride, mesitylene is formed together 
with about four times the quantity of pseudocumene. 
In order to prepare mesitylene, one volume of commercial 
acetone is mixed with dry sand in a large tubulated retort, a 
cold mixture of one volume of sulphuric oi and half a volume 
of water being then allowed to flow into the retort in a slow 
unbroken stream. The liquid is allowed to stand for twenty- 
four hours and then distilled; the first distillate consists of 
acetone and water, but is followed by the crude mesitylene, the 
receiver being changed as soon as oily bands appear in the retort. 
The distillate 1s washed with water and caustic soda, dried and 
purified by fractional distillation.* 
Mesitylene is a strongly refractive liquid, which has a 
characteristic, not unpleasant odour, and boils at 168° It is 
oxidized by dilute nitric acid to mesitylenicacid,C,H,(CH,),CO,H, 
and uvitic acid, C,H,(CH,)(CO,H),, while chromic acid solution 
converts it into trimesic acid, C,H,(CO,H)s. 
When picric acid is dissolved in hot mesitylene, the compound 
C,H,,.+ C,H,(NO,),0 separates on cooling in yellow plates.® 
Hexhydromesitylene, C,H,(CH,)3, is obtained by heating 
mesitylene to 280° with phosphonium iodide. It is a liquid, 
which boils at 135°—138° and is not attacked by fuming nitric 
acid in the cold, but is converted into trinitromesitylene on 
warming.® 
1 Claisen, Ber. Deutsch, Chem. Ges. vii. 1168 ; Jacobsen, ibid. x. 885. 
* Fittig and Schrohe, ¢béd. viii. 17. 

3 Fittig and Briickner, Ann. Chem. Pharm. exlvii. 42. 

4 Fittig, zbid. exli. 132. 


5 Robinet, Compt. Rend. xcvi. 500. 
6 Baeyer, Ann. Chem. Pharm. cly. 273. 


PSEUDOCUMENE. — 105 


a-Trimethylbenzene or Pseudocumene was first synthetically pre- 
pared by Ernst and Fittig, who brominated coal-tar xylene and 
treated the product with methyl iodide and sodium.t It may 
be obtained in this way both from bromoparaxylene? and from 
bromometaxylene,? as well as from the dibromotoluene, which is 
formed by the direct bromination of toluene.* 

It is also a product of the action of aluminium chloride and 
methyl chloride on paraxylene and orthoxylene, while metaxylene 
yields mesitylene in addition.? Jacobsen has shown that the 
cumene, which is formed when phoron, C,H,,O0, is heated with 
zinc chloride or phosphorus pentoxide, is identical with pseudo- 
cumene, while mesitylene is obtaimed when sulphuric acid is 
employed.® 

In order to separate it from coal-tar naphtha, the fraction 
which boils at 160°—168° is heated to 80°—90° with an equal 
volume of sulphuric acid, the mixture being well-agitated. 
Jacobsen found as the result of one experiment’ that 390 ccm. 
are thus dissolved out of a total volume of 540 ccm. of the mixed 
hydrocarbons. The solution in sulphuric acid is then diluted 
with 180 ccm. of water, the lquid being well cooled; after 
about twenty-four hours, the lower layer, which consists almost 
entirely of dilute sulphuric acid, is removed and an additional 
quantity of 120 ccm. of water added to the residue. The liquid 
is then heated until the crystalline crust which has formed is 
redissolved and is then allowed to stand. The pseudocumene- 
sulphonic acid separates out after some time, and a further 
quantity can be obtained by the concentration of the mother- 
hquor; thus, in the experiment mentioned above, 194 grms, 
were deposited during two days, while a second crop consisted 
of 18 grs. This product is then purified by recrystallization 
from dilute sulphuric acid. Mesitylenesulphonic acid and a 
little pseudocumenesulphonic acid remain in the mother-liquor. 
The pure hydrocarbon is liberated by heating the purified 
sulphonic acid to 173°—175° with hydrochloric acid or sub- 
mitting it to dry distillation. The mixed sulphonic acids, from 
which the sulphuric acid has been removed by the addition of 
water in the way described, may also be heated to 100° with 

1 Baeyer, Ann. Chem. Pharm. exxxix. 148. 
2 Fittig and Jannasch, zbid. cli. 283. 

3 Fittig and Laubinger, zbid. cli. 257. 

4 Jannasch, ibid, clxxvi. 286. 


5 Jacobsen. Ber. Deutsch. Chem. Ges. xiv. 2628. 
6 Ibid. x. 855. 7 Ann. Chem. Pharm. clxxxiv. 199. 


106 AROMATIC COMPOUNDS. 





hydrochloric acid, the mesitylene derivative alone being de- 
composed at this temperature.* 

Pseudocumene has also been found in rock-oil from Burmah, 
and occurs, together with mesitylene, in all rock-oils which have 
hitherto been examined; American illuminating oil contains 
about 0°2 per cent. of this trimethylbenzene.2 Pseudocumene — 
boils at 169°5°;? it is oxidized by dilute nitric acid to xylic 
acid, paraxylic acid, C,H,(CH,;),CO,H, and xylidic acid, 
C,H,(CH,)(CO,H),. 

v-Trimethylbenzene or Hemellithene was prepared by Jacobsen 
by the distillation of a-isodurylic acid, C,H,(CH,),CO,H, with 
lime,* and was also detected by him in coal-tar. In order to 
prepare it, the fraction, which boils between 172°—180", after 
repeated distillation is dissolved in warm sulphuric acid and 
the solution diluted until the mixed sulphonic acids crystallize 
out. They are then converted into the barium salts, from which 
the sodium salts, and finally the sulphamides, are prepared and 
readily obtained in the pure condition, pseudocumenesulphamide 
melting at 181°, and the corresponding hemellithene derivative 
‘at 195°. The separation may be still more easily effected by 
converting the more difficultly soluble portion of the barium 
‘salt into the sodium salt and fractionally precipitating this with 
barium chloride until a sulphamide melting below 195° can no 
longer be prepared from the precipitate ; the solution then con- 
tains the sodium sulphonate of hemellithene alone, and this is 
finally decomposed by heating with hydrochloric acid.® 

It is a liquid boiling at 175°—175°5°, which does not solidify 
at —20° and is oxidized by dilute nitric acid to hemellithic acid, 
i(C,H,(CH,),CO,H. 

Hexhydrocumene, C,H,., 1s the name given by Renard to a hydro- 
‘carbon which occurs with other similar compounds (Pt. IV. p. 6) 
in resin-spirit and boils at 147°—150°" It is probably an 
addition-product of pseudocumene or hemellithene. 


1 Armstrong, Ber. Deutsch. Chem. Ges. xi. 1967. 

2 Engler, dbid. xviii. 2234; see also Markownikow, Ann. Chem. Pharm. 
ecxxxiv. 89. - 3 Jacobsen, zbid. xix. 2513. 

4 Ibid, xv. 1857. 5 Ber. Deutsch. Chem. Ges. xix. 2511. 

me bid. xix, 2520, 7 Ann. Chim. Phys. [6], i. 229. 


TRICHLOROMESITYLENE. 107 


HALOGEN SUBSTITUTION PRODUCTS OF THE 
TRIMETHYLBENZENES. 


2329 Dry chlorine acts very energetically upon cooled mesity- 
lene, a mixture of mono-, di- and trichloromesitylene being 
formed. When the product is washed with caustic soda and 
dissolved in boiling alcohol, almost the whole of the trichloro- 
mesitylene separates on cooling. The greater portion of the 
alcohol is then removed from the filtrate by distillation and the 
residue precipitated with water, the compounds deposited being 
separated by fractional distillation. 

Monochloromesitylene, C,H,C!(CH,),, is a colourless liquid, 
which boils at 204°-—206° and does not solidify at - 20°. Boiling 
chromic acid solution oxidizes it gradually to acetic acid, while 
dilute nitric acid converts it into chloromesitylenic acid,. 
C,H,Cl(CH,),CO,H. 

Dichloromesitylene, C,HC1,(CH;),, crystallizes from . alcohol 
in splendid, lustrous prisms, melting at 59°. It boils at 243°— 
244°, but readily volatilizes at the ordinary temperature. It is 
scarcely attacked by a boiling solution of chromic acid. 

Trichloromesitylene, C,Cl,(CH3)3, was prepared by Kane, who 
named it pteleyl chloride, C,H,Cl, because he believed that the 
radical of this substance was also contained in ulmic acid 
(wlmus, mreX€a), a decomposition product of woody fibre. 

It is also obtained, together with hexmethylbenzene, by the 
action of methyl chloride on a mixture of aluminium chloride 
and orthodichlorobenzene. In order to explain this remarkable 
formation, it may be assumed that the following reaction among 
others takes place : 


C.H,Cl, + Al,Cl, = C,H,C1ALCl; + Cl. 


The monochloromesitylene which is first formed is then further 
chlorinated.” 

Trichloromesitylene crystallizes from boiling alcohol in fine 
needles, melts at 204°—205°, boils at 280° and readily sublimes 
in lustrous needles, It is scarcely attacked by boiling nitric 
acid, chromic acid or alkaline permanganate. 


1 Fittig and Hoogewerff, Ann. Chem. Pharm. cl. 323. 
2 Friedel and Cratfts, Ann. Chim. Phys. [6], x. 411. 


108 AROMATIC COMPOUNDS. 


Monobromomesitylene, C,H,Br(CH,)3, is formed by the action 
_ of bromine on well-cooled mesitylene.1 According to Schramm, 
it is best prepared by gradually adding a molecule of bromine to 
one of mesitylene in the dark.? It is a liquid, which has a faintly 
aromatic odour, boils at 227° and solidifies on cooling in crystals, 
which melt at —1°. 

Dibromomesitylene, C,HBr.(CH3),, was obtained by Fittig and 
Storer, together with the preceding compound and tribromo- 
mesitylene. Schramm found that it is obtained in the pure 
state when monobromomesitylene is treated in the dark 
with the calculated amount of bromine. It crystallizes from 
alcohol in long, brittle needles, melts at 64° and boils at 
285°. 

Tribromomesitylene, C,Br,(CH;),, was obtained by Hofmann 
and Cahours, and is readily formed when three molecules of 
bromine are added to one molecule of mesitylene in the dark. 
It is only slightly soluble in boiling alcohol, from which it crys- 
tallizes in thin, brittle needles, while it separates from hot 
benzene, in which it is more readily soluble, in small mono- 
symmetric prisms, melting at 224°. 

Monochloropseudocumene, C,H ,Cl(CH,),, has been prepared 
by Haller from a-pseudocumidine by means of Sandmeyer’s 
reaction (Pt. III. p. 264); it forms lustrous scales or plates, 
melting at 71°—72°? 

a-Monobromopseudocumene, C,H,Br(CH,)., (CH, : CH, : CH, : 
Br=1:2:4:6), is best obtained by the action of bromine on 
pseudocumene in the dark. It crystallizes from hot alcohol in 
large plates, which show a play of colours, melt at 73° (Beilstein 
and Kogler; Haller; Schramm) and boils at 236°—238°.4 

s-Monobromopseudocumene (1:2:4:5). A monobromosul- 
phonic acid is formed, together with the dibromosulphonic 
acid, by the action of sulphuric acid on dibromopseudocumene, 
and this yields s-monobromopseudocumene on heating with 
hydrochloric acid. It is a liquid boiling at 236°—238° 
(Jacobsen). 

v-Monobromopseudocumene (1: 2:4:38), is obtained by the bro- 
mination of a-pseudocumenesulphoniec acid and the decomposi- 
tion of the product with superheated steam,as an almost odourless 
liquid, boiling at 226°—229°.6 

1 Fittig and Storer, Ann. Chem. Pharm. exlvii. 6. 


2 Ber. Deutsch. Chem. Ges. xix. 212. 3 Tbid. xviii. 98. 
4 Jacobsen, cbid. xix. 1223. 5 Kelbe, zbid. xix. 1546. 


NITROMESITYLENE. 109 





Dibromopseudocumene, C,HBr,(CH;), (1:2: 4:5 :6), is formed, 
together with the following compound, when pseudocumene is 
treated with bromine in the dark or in diffused daylight. It is 
tolerably soluble in alcohol, crystallizes in long, flat, lustrous 
and very pliant needles, melts at 61°3° (Schramm) and boils at 
293°—294° (Jacobsen). 

Tribromopseudocumene, O,Br,(CH,),, is also only slightly soluble 
in boiling alcohol, and crystallizes when the solution is gradually 
cooled in very thin, long, pliant needles, melting at 225°—226° 
(Fittig and Laubinger). 

Tribromohemellithene, CBr,(CH,)3, crystallizes from hot alcohol 
in long, fine needles, melting at 245°.1 


NITROTRIMETHYLBENZENES. 


2330 Mononitromesitylene, C,;H,(NO,)(CH,)3, was obtained in 
the impure state by Kane, who overlooked the presence of 
nitrogen in it and named it mesitaldehyde, C,H,O. Cahours 
and Hofmann also failed to prepare this substance pure. It is 
formed when mesitylene is heated with nitric acid of sp. gr. 1°38, 
and in considerable quantity as a by-product in the preparation 
of mesitylenic acid from which it is separated by means 
of its greater volatility with steam.? It can also be obtained 
from dinitromesitylene by reducing the latter to nitro-amido- 
mesitylene, dissolving this in cold alcohol and treating the solution 
with nitrogen trioxide until the liquid smells distinctly of ethyl 
nitrite. It is then heated on the water-bath until the evolution 
of nitrogen ceases, the nitromesitylene precipitated with water 
and finally distilled with steam.® 

It is tolerably soluble in cold, in almost every proportion in 
boiling alcohol, and crystallizes in transparent, lustrous, yellow 
prisms, which are tolerably thick and often an inch in length, 
while it sometimes forms large tablets, melts at 44° 4 and boils at 
255° (Ladenburg). 

Dinitromesitylene, C,A(NO,).(CH,)3, which was discovered by 
Hofmann,’ is very readily formed when mesitylene is allowed to 


1 Jacobsen, Ber, Deutsch. Chem. Gles. xix. 2520. 

2 Fittig and Storer, Ann. Chem. Pharm. exlvii. 1. 

3 Ladenburg, ibid. clxxix. 170. 

* Biedermann and Ledoux, Ber. Deutsch. Chem. Ges. viii. 57. 
> Ann. Chem. Pharm. xxi. 130. 


110 AROMATIC COMPOUNDS. 


drop into well-cooled, fuming nitric acid ; the solution is poured 
into cold water after standing for some time, and the curdy pre- 
cipitate washed with water. It crystallizes from hot alcohol in 
colourless, lustrous, rhombic, prisms, often an inch in length, which 
melt at 86°. “The extreme readiness with which mesitylene is 
completely converted in the cold into this splendid crystalline 
compound is so characteristic that it affords the best means of 
detecting the hydrocarbon.” + 

Trinitromesitylene, C,(NO,),(CH,)3, was discovered by 
Cahours,? and carefully investigated by Hofmann and Fittig. 
It is obtained in a similar manner to the dinitro-compound 
when a mixture of one volume of fuming nitric acid with two 
volumes of concentrated sulphuric acid is employed, the forma- 
tion being complete after a few seconds. It is almost insoluble 
in cold alcohol and very slightly soluble in hot alcohol, from 
which it crystallizes in fine, white needles, melting at 230°—232°. 
It separates from hot acetone, in which it is more readily soluble 
in large, transparent, vitreous prisms, belonging to the asymmetric 
system. 

a-Mononitropseudocumene, C,.H.,(N O,)(CH,)3,(CH, : CH, : CH, : 
NO,—=1: 2:4: 5), isreadily formed when pseudocumene is dissol- 
ved in concentrated nitric acid * and crystallizes from alcohol in 
long, strongly refractive prisms, which melt at 71° and become 
coloured yellow on exposure to the light. It boils at 265°, 
and is not further acted upon by nitric acid in the cold, while 
mesitylene under these conditions is immediately converted into 
the dinitro-compound. 

It is converted by the action of zinc dust on its solution m 
alcoholic potash into azopseudocumene, C,,H,,N,, which separates 
from glacial acetic acid in fine, reddish yellow crystals, melts 
at 173°—174° and is converted by further reduction into 
the colourless hydrazopseudocumene, which melts at 124°— 
125° 

B-Mononitropseudocumene, (1:2: 4:6), has been prepared from 
a-nitropseudocumidine by means of the diazo-reaction, and forms 
compact prisms, melting at 20°. 

y-Mononitropseudocumene, (1:2: 4:3), is obtained in a similar 

1 Fittig, Ann. Chem. Pharm. exli. 132. 2 Ibid. \xix. 241. 


3 Bodewig, Jahresb. Chem. 1879, 369. 

* Schaper, Zeitschr. Chem. 1867, 12; Fittig and Laubinger, Ann. Chem. 
Pharm. cli. 259. 

5 Pospjechow, Ber. Deutsch. Chem. Ges. xx. Ref. 217. 

6 Edler, ibid. xviii, 629. 


TRINITROPSEU DOCU MENE. 111 


manner from y-nitropseudocumidine, and forms yellow crystals, 
melting at 30°. 

Trinitropseudocumene, C,(NO,),(CH,)3, is formed by allowing 
pseudocumene to drop into a mixture of nitric and sulphuric 
acids, the liquid being subsequently warmed. It is also very 
slightly soluble in boiling alcohol, from which it crystallizes in 
small, colourless needles, united in stellate groups. It crystallizes 
from hot benzene in hard, tolerably thick, transparent, quadratic 
prisms, which melt at 185°, and sublime ata higher temperature. 
These crystals are a very characteristic derivative of pseudo- 
cumene ; if a mixture of this with mesitylene be nitrated by the 
method described, the trinitro-compounds can readily be separated 
by recrystallization from benzene, since the needles of trinitro- 
mesitylene can readily be distinguished and mechanically 
separated from the compact crystals of trinitropseudocumene.? 
According to Engler, who has employed this method to detect 
these hydrocarbons in rock-oils, a mixture of the trinitro- 
compounds melts at 167°. In order to decompose this into its 
constituents, it is heated on the water-bath for several hours 
with a quantity of alcohol which is insufficient for complete 
solution, the trinitropseudocumene being dissolved while the 
trinitromesitylene remains behind. When pseudocumene is 
boiled with fuming nitric acid, a liquid substance is formed in 
addition to trinitropseudocumene ; this is probably dinitropseudo- 
cumene, but could not be obtained in the pure state (Fittig and 
Laubinger). 

Trinitrohemeltithene, C.(NO,)3(CH,),. The first product of the 
action of a mixture of nitric and sulphuric acids on hemellithene 
is a mononitro-derivative, melting at about 100°, which is con- 
verted by the further action of the acid, finally assisted by heat 
into the trinitro-compound. This crystallizes from hot alcohol 
in compact prisms, which have a vitreous lustre and melt at 209° 
- (Jacobsen). 


1 Mayer, Ber. Dewtsch. Chem. Ges. xx. 966. 
2 Fittig and Wackenroder, zbzd. cli. 295. 


112 . AROMATIC COMPOUNDS. 


TRIMETHYLBENZENESULPHONIC ACIDS, 
C,H,(CH,),80,H. 


2331 Mesitylenesulphonic acid was first prepared by Hofmann 
by dissolving mesitylene in fuming sulphuric acid, and was 
subsequently studied by Fittig, Jacobsen and Rose.’ It forms 
rhombic tablets, melts at 77° and contains two molecules of 
water, which are lost over sulphuric acid. The salts crystallize 
well. 

Mesitylenesulphonie chloride, C,H,(CH3),50,Cl, crystallizes 
from ether in large, wedge-shaped needles, melting at 57°. 

Mesitylenesulphamide, C,H,(CH,),50,.NH,, is soluble in 8000 
parts of water at 0° andin 185 parts of boiling water, from which 
it crystallizes in long, hair-like needles. It dissolves much more 
readily in alcohol and is deposited from this solution as a mass, 
which after drying is fibrous and resembles asbestos, melts at 
141°—142° and readily sublimes to a voluminous crystalline mass. 
On heating to 160°—165° with hydrochloric acid, it decomposes 
into ammonia, sulphuric acid and mesitylene. This compound 
may be employed for the separation of mesitylene from -pseudo- 
cumene, since the sulphamide of the latter is less soluble in 
water and alcohol. One hundred parts of 83 per cent. alcohol 
dissolve : 


Mesitylenesulphamide. Pseudocumenesulphamide. 
AGO phous pete tellin cle mene Det? 
At the boiling-point. . 113°65 22°73 


Mesitylenedisulphonice acid, C,H(CH3),(SO,H),, 1s formed by 
heating mesitylene with ten parts of fuming sulphuric acid to 
30°—40° for two or three days, during which time three to four 
parts of phosphorus pentoxide are added in small quantities 
every ten hours. It crystallizes in deliquescent needles. The 
potassium salt, C,H(CH3;).(SO,K), + 2H,O, decomposes almost 
quantitatively on heating, mesitylene being formed :* 


C,H(CH,),(SO,K), + 2H,0°= C,H,(CH,), + 280,KH. 


1 Ann. Chem. Pharm. elxiv. 538. 

2 Holtmeyer, Zeitschr. Chem. 1867, 686. 

3 Jacobsen, Ann. Chem. Pharm. clxxxiv. 184. 
4 Barth and Herzig, Monatsh. Chem. i. 808. 


a-PSEUDOCUMENESULPHONIC ACID. 113 





a-Pseudocumenesulphonie acid, (CH,:CH,:CH,:SO,H=1 :2:4:5 
4:5). The preparation of this substance has already been de- 
scribed. It crystallizes in cubes, is only slightly soluble in dilute 
sulphuric acid and melts at 111°—112°1 

a-Pseudocumenesulphonie chloride, C,H,(CH,),50,Cl, separates 
from ether in large, transparent, monosymmetric prisms, melting 
Bie GL 

a-Pseudocumenesulphamide, C,H,(CH;),50,.NH,, dissolves in 
7000 parts of cold, and 380 parts of boiling water; it is only 
slightly soluble in cold, more readily in hot alcohol, from which 
it crystallizes in short, hard, transparent prisms, which are de- 
composed by hydrochloric acid at 173°—175° with regeneration 
of pseudocumene (Jacobsen). 

8-Pseudocumenesulphonic acid (1:2:4:6) is obtained by dis- 
solving a-bromopseudocumene in fuming sulphuric acid and 
treating the sodium salt of the bromosulphonic acid with 
ammonia and zinc dust. Its barium salt is tolerably soluble 
in water. 

8-Pseudocumenesulphamide separates from hot alcohol as a 
soft crystalline mass, consisting of fine prisms, and crystallizes 
from a mixture of benzene and alcohol in thick prisms, which 
melt at 178°—179°3 

ry-Psewdocumenesulphonic acid (1:2:4:3) has been prepared 
from dibromopseudocumenesulphonic acid, and forms a readily 
soluble sodium salt. 

y-Pseudocumenesulphamide forms small flat needles or plates, 
melting at about 113° (Jacobsen), 

Hemellithenesulphonie acid (1:2:3:5) crystallizes from dilute 
sulphuric acid in oblique, six-sided tablets, containing water of 
crystallization, and forms a difficultly soluble barium salt. 

Hemellithenesulphamide crystallizes from hot alcohol in short, 
hard, transparent prisms, which are even less soluble in cold 
alcohol than pseudocumenesulphamide and melt at 195° It 
yields two sulphaminehemellithic acids on oxidation. 

1 Kelbe and Pathe, Ber. Deutsch. Chem. Ges, xix. 1546. 
2 Radlof, <bzd. xi. 32. 


3 Jacobsen, zbid. xix. 1218 ; Kelbe and Pathe, 7zbid, xix. 1546. 
4 Jacobsen, tbid, xv. 1858 ; xix. 2511 and 2517. 


114 AROMATIC COMPOUNDS. 


TRIMETHYLHYDROXYBENZENES, 0,H,(CH,),OH. 


2332 Mesitol has been obtained by means of the diazo-re- 
action from amidomesitylene or mesidine! and by fusing mesity- 
lenesulphonic acid with caustic potash.? It forms crystals, 
which smell like phenol and melt at 68°—G69°, is readily volatile 
with steam, boils at 219°5° and gives no colouration with ferric 
chloride. 

Nitromesitol, C,H(NO,)(CH,),0H, which has been prepared 
from nitromesidine by means of the diazo-reaction, crystallizes 
from hot water in yellow plates, which melt at 64° and are readily 
volatile with steam. 

Amidomesitol, C,A(NH,)(CH,),0H. The hydrochloride of this 
base, which crystallizes in needles, is formed by the action of tin 
and hydrochloric acid on nitromesitol; the free base forms 
crystals, which readily change into a resinous mass.® 

a-Pseudocumenol (CH,: CH, : CH,: OH =1:2:4:5) is ob- 
tained by fusing pseudocumenesulphonic acid with caustic 
potash, and has also been prepared from a-pseudocumidine by 
means of the diazo-reaction.® It forms fine, pliant needles 
which smell like phenol, melts at 73° (Auwers) and boils at 
232°. It gives no colouration with ferric chloride, and on 
fusion with caustic potash is converted into hydroxy-xylic acid, 
which decomposes into carbon dioxide and a-metaxylenol when 
heated with hme. 

Pseudocumenyl methyl ether, C,H,(CH;),0CH,, is formed by 
heating a solution of a-cumidine in methyl alcohol with 
sulphuric acid and potassium nitrite. It is a liquid, which 
possesses a pleasant aromatic odour® and boils at 209°—211° 
(Auwers). 

Nitro-a-pseudocumenol, C,(CH;),H(NO,)OH (1:2:4:3:5). 
When a-pseudocuminol is brought into well-cooled, fuming 
nitric acid, nitropseudocumenyl nitrate, C,(CH;),H(NO,)ONO,, 
is formed by a singular reaction. This substance crystallizes 

1 Biedermann and Ledoux, Ber. Dewtsch. Chem. Ges. viii. 57. 
2 Ibid. viii. 250 ; Jacobsen, Ann. Chem. Pharm. exev. 265. 
3 Knecht, Ber. Deutsch. Chem. Ges. xv. 1875. 

4 Reuter, zbid. xi. 29. 


> Liebermann and Kostanecki, bid. xvii. 885 ; Auwers, ibid. xvii. 2976. 
® Hofmann ibid. xvii. 1918. 


TRIMETHYLHYDROXYBENZENES, 115 


from ether in lustrous, rhombic tablets or prisms, which melt at 
84° with decomposition and are converted into nitropseudo- 
cumenol by evaporation with alcohol on the water-bath. The 
latter crystallizes in long, reddish yellow needles or prisms, which 
have a fatty lustre, melt at 48° and are reconverted into the 
nitrate by heating with dilute nitric acid. This substance is 
also prepared by the action of nitric acid on pseudocumenyl 
methyl ether. 

Dinitropseudocumenol, C.(CH,),(NO,),OH, is obtained from the 
metameric nitrate by the action of ammonia, a small amount 
of nitropseudocumenol and a resinous substance being also 
formed. It crystallizes from alcohol in yellow, cross-shaped or 
fascicular groups of needles, melting at 112°" It forms a 
deep red-coloured solution in alkalis, from which it is repre- 
cipitated by acid. 

Amido-a-pseudocumenol, C,(CH,).H(NH,)OH, is obtained when 
a-cumenol is acted upon by a diazo-salt and the resulting 
phenylazopseudocumenol, C,H;.N,.C;(CH,),H(OH), reduced 
with tin and hydrochloric acid (Liebermann and Kostanecki), 
and may be obtained in a similar manner from the nitrate 
described above. It is a crystalline substance, which sublimes in 
needles, melts at 166°—167° and gives a reddish violet coloura- 
tion with Liebermann’s reagent. 

B-Pseudocumenol (1:2:4:6) has been prepared from #- 
pseudocumidine * and 8-pseudocumenesulphonic acid ;* it forms 
crystals, melting at 95°, and boils at 230°—231°. 

y-Pseudocumenol (1:2:4:3) has been obtained both from the 
corresponding pseudocumidine* and sulphonic acid (Jacobsen). 
It crystallizes from ether in long needles, melts at 62° and boils 
at 232°—234°, It gives no colouration with ferric chloride. 

Hemellithenol (L:2:3:5) was prepared by Jacobsen from the 
sulphonic acid ; it crystallizes from alcohol in long, flat needles, 
melting at 81°, and gives no colouration with ferric chloride. 


1 Auwers, Ber. Deutsch. Chem. Ges. xviii. 2655. 2 Edler, zbid, xviii. 629. 
3 Jacobsen, zbid. xix, 1218. 4 Engel, ibid. xviii. 2229. 


116 AROMATIC COMPOUNDS. 





TRIMETHYLDIHYDROXYBENZENES. 


2333 Pseudocumenequinol, C,H(CH,),(O0H,). The correspond- 
ing quinone is formed by the oxidation of isodurenol,’ C,H(CHs), ~ 
OH, and isoduridine,? C,H(CH,),NH,, as an oily yellow liquid, 
which possesses the characteristic odour of the quinones and 
solidifies on cooling to a crystalline mass, melting at 11°. It is 
converted by sulphur dioxide into the quinol, which crystallizes 
from hot water in splendid white needles, melting at 169°. 

Nitropseudocumenequinol, C,(NO,)(CH,),(OH),. When pseudo- 
cumenecarboxylic acid, C,(CH,),0,.CO,H, is heated with con- 
centrated nitric acid, nttropsewdocumenequinone, C,(NO,)(CH3),0,, 
is obtained, its formation by this reaction corresponding to that of 
nitranilic acid from dihydroxyterephthalic acid (Vol. III. Pt. IV. 
p. 520). The quinone forms golden yellow plates, which melt at 
113° and readily sublime, and is converted by sulphur dioxide 
into the quinol, which crystallizes in long, golden-yellow needles 
and melts at 106.°° 

Mesorcinol, C,H(CH,),(OH),, is readily formed when amido- 
mesitol hydrochloride is dissolved m water and treated with the 
theoretical quantity of sodium nitrite at a low temperature ; 
nitrogen is evolved and the reaction must be completed by boil- 
ing. Mesorcinol is readily soluble in ether, slightly in cold and 
readily in hot water, sublimes in dazzling white plates, melting 
at 149°—150°, and boils at 274°—275°. If its solution be treated 
with ferric chloride and distilled, hydroxymetaxyloquinone 
(Vol. IIL. Pt. IV. p. 404) 1s formed and can readily be recognized 
by its characteristic reactions. On heating it with sulphuric 
acid a colouring-matter is produced, which forms a red solution 
in alkalis; the dilute rose-red solution shows a deep green 
fluorescence.‘ 

1 Hofmann, Ber. Deutsch. Chem. Ges. xvii. 1916. 
2 Nolting and Baumann, 7bid. xviii. 1152. 


3 Nef, Ann. Chem. Pharm. ecxxxvii. 17. 
4 Knecht, zbid. xy. 1875. 


AMIDOTRIMETHYLBENZENES. 117 


AMIDOTRIMETHYLBENZENES. 


2334 Amidomesitylene or Mesidine, C,H,(CH;),NH,, is formed 
by the reduction of nitromesitylene (Fittig and Storer), as well 
as by heating trimethylphenylammonium iodide to the melting 
point of lead,! and occurs in varying quantities in crude cumi- 
dine It is a. liquid which boils at 229°—230°% and has 
almost the same specific gravity as water. 

Dimethylmesidine, C,H,(CH,),N(CH,),, 1s a liquid, boiling at 
213—214°, which does not combine with methyl iodide even at 
150° (Hofmann). 

Acetmesidide, C,H,(CH,),NH(C,H,0), crystallizes from hot 
alcohol in broad prisms, melting at 216°—217°. 

Mesitylearbimide, CyH,(CH,),NCO. The product of the 
action of ethylchlorocarbonate or mesidine is mesitylwrethane, 
C,H,(CH;),NH.CO.OC,H,, which forms needles, melting at 
61°—62° and is converted into mesitylearbimide by heating with 
phosphorus pentoxide. This is a liquid, which has a pungent 
odour, boils at 218° — 220° and becomes turbid after a short time, 
a gelatinous mass being deposited (Kisenberg). 

Mesityl mustard oil, C,H,(CH,),NCS, was prepared by 
Kisenberg by heating mesidine with carbon disulphide and 
alcoholic potash. It crystallizes in long, lustrous needles, which 
have a faintly pungent odour and melt at 64°. 

Nitromesidine, C,H(NO,)(CH3),NH,, was obtained by Maule 
from dinitromesitylene by passing sulphuretted hydrogen into 
its alcoholic solution. The reaction only proceeds slowly ® and 
is not greatly accelerated by the addition of ammonia (Laden- 
burg). Nitromesidine crystallizes from alcohol in golden 
yellow needles, which melt at 73°—'74° and are not decomposed 
by boiling caustic soda. 

Nitro-acetmesidide, C,H(NO,)(CH,),NH(C,H,0), is formed 
when acetmesidide is heated with nitric acid to which a little 
water has been added (Ladenburg), or when its solution in 


1 Hofmann, Ber. Dewtsch. Chem. Ges. v. 715 3 viii. 61. 

2 Eisenberg, zbid. xv. 1011; Inauguraldissert. Berlin, 1882; Engel, Ber. 
Deutsch. Chem. Ges. xviii. 2229. 

8 Ladenburg, Ann. Chem. Pharm. elxxix. 163. 
_ * Ibid. xiii. 137. 

5 ieee and Ledoux, Ber. Deutsch. Chem. Ges. viii. 57; Knecht, cbid. 
xv. 1375. 


118 AROMATIC COMPOUNDS. 


glacial acetic acid is treated with fuming nitric acid (Biedermann 
and Ledoux). It crystallizes from boiling alcohol in silky 
needles or small prisms, which melt at 191° and are not decom- 
posed by boiling with alkalis. It is a weak base, which dissolves 
in concentrated hydrochloric and is reprecipitated by ammonia 
but not by water alone. It decomposes into acetic acid and 
nitromesidine when it is heated to 150° with hydrochloric acid. 

Dinitromesidine, C,(NO,),CH;),NH,, was obtained by Fittig 
by the reduction of trinitromesitylene with ammonium sulphide. 
It crystallizes from hot alcohol in lustrous, yellow needles, 
melting at 193°—194°. 

Dinitro-acetmesidide, C(NO,).(CH;),NH(C,H,0), is prepared 
by dissolving the mononitro-compound ina mixture of nitric and 
sulphuric acids, and crystallizes from hot alcohol in dazzling 
white needles, which melt at 275° and are resolved into acetic 
acid and dinitromesidine by heating with hydrochloric acid 
(Ladenburg). 

Diamidomesitylene, C,H(CH,)3(NH,),, 1s formed by the action 
of tin and hydrochloric acid on dinitromesitylene (Fittig) and 
on trinitromesitylene (Ladenburg), ammonia being in this case 
eliminated. It crystallizes from hot water in hair-like needles 
and separates from an ethereal solution in transparent, monosym- 
metric crystals, which melt at 90° and sublime in lustrous 
needles when carefully heated. Chronic acid solution oxidizes 
it to hydroxymetaxyloquinone ; its salts crystallize well. 

Nitrodiamidomesitylene, C,(NO,)(CH3),(NH,),, 1s obtained by 
the further action of ammonium sulphide on dinitromesidine. 
Its crystallizes from hot water, in which it is only slightly 
soluble, in large, orange-red plates, and separates from alcohol on 
the spontaneous evaporation of the solution in very large, well- 
formed monosymmetric crystals, which are perfectly trans- 
parent, possess a diamond lustre and are of nearly the same 
colour as sodium nitroprusside, this substance being one of the 
most beautiful of organic compounds. It melts at 184° and is 
a well characterised base, its hydrochloride, C,H,(NO,)(NH,), 
(C1H),, forms colourless or pale yellow, quadratic tablets 
(Fittig). 

2335 a-Pseudocumidine (CH,:.CH,: CH,: NH, =1: 2; 4: 
5) was obtained by Schaper by the reduction of a-nitro- 
pseudocumene. It is manufactured by heating commercial 
xylidine to 250° with hydrochloric acid and methyl alcohol. 
The difficultly soluble nitrate of a-pseudocumidine is then pre- 


a-PSEUDOCUMIDINE, 119 


pared from the crude cumidine, which contains isomeric bases, 
and is finally decomposed by caustic soda.’ The crude cumidine 
may also be fractionated and the portion boiling between 232°-— 
235° purified by washing with alcohol.” 

a-Pseudocumidine crystallizes from hot water in long, silky 
needles, and from alcohol in large, lustrous, transparent prisms, 
melts at 68° and boils at 234° (Auwers). It is employed in the 
manufacture of azo-dyes. Its salts crystallize well. On oxidation 
with potassium ferricyanide it is converted into the azopseudo- 
cumene which has been previously mentioned (Pospjechow). 

Methylpseudocumidine, C,H,(CH3),N H(CH,), melts at 44° and 
boils at 237°. 

Dimethylpseudocumidine, C,H,(CH,),N(CH;),, is an oil, which 
has a pleasant smell of flowers and boils at 222° (Hofmann). 

a-Acetpseudocumide, C,H,(CH,),NH(C,H,0), crystallizes in 
compact, white needles, melting at 164° (Auwers). 

a-Nitropseudocumidine, OC,H(NO,)(CH,),NH,. When the 
preceding compound is nitrated, nztro-acetpseudocumide is formed 
and crystallizes in long, yellowish prisms, melting at 202°—204° 
(Auwers). This is converted by hydrolysis into nitropseudo- 
cumidine, which separates from alcohol in large, red, asymmetric 
crystals, melting at 46°—47°. 

a-Diamidopseudocumene, C,H(CH,),(NH,),(1: 2: 4: 5: 6), 
has been prepared by the reduction of a-nitropseudocumidine, 
It crystallizes from hot water in colourless needles, melting at 
about 90°; a very dilute solution of its hydrochloride is coloured 
deep red by ferric chloride, and the dry, perfectly neutral salt 
evolves hydrochloric acid when it is heated with benzaldehyde. 
The base is therefore an orthodiamine (Vol. III. Pt. IV. p. 62), 
which is also proved by the fact that nitro-acetpseudocumide is 
converted by reduction into ethenyldiamidopseudocumene : 


NO, 
C,H(C ++ 6H 7 > 


Hy) 
*°\\NH.CO.CH, 


Ne 
CH(CH COOH, + 3H,0. 


The compound obtained in this way is not decomposed by 
boiling alcoholic potash. 
1 Hofmann, Ber. Deutsch. Chem. Ges. xvii. 2985. 
2 Auwers, zbid. xviii. 2661. 3 Edler, ibid. xviii. 629. 
274 


120 AROMATIC COMPOUNDS. 


a-Dinitropseudocumidine, C,(NO,).(CH;),NH,. The further 
nitration of nitro-acetpseudocumide yields dinitro-acetpseudo- 
cumide, which melts at 280° and on heating with sulphuric acid 
is converted into dinitropseudocumidine, which crystallizes from 
alcohol in long, lustrous, orange-yellow needles, melting at 
183°. It has only feeble basic properties and is converted by 
reduction into a strong base, which has not yet been thoroughly 
investigated. 

Pseudocumylhydrazine, C,H.CH,),N,H;, is prepared from 
a-cumidine by Fischer’s method; it crystallizes from ether in 
needles, melting at 120°. This compound was prepared in 
order to determine whether technically prepared cumidine is 
identical with that obtained from pseudocumene, and for this 
purpose was converted into the hydrocarbon according to a 
method proposed by Baeyer. This consists in adding four 
parts of water to the hydrazine, heating to boiling and gradually 
adding a 10 per cent. solution of copper sulphate : 


C.H,(CH,),NH.NH, + 2CuS0,+H,O = 
C,H,(CH,), + Cu,0 + N, + 2H,S0,. 


Pure pseudocumene was obtained in this way.” 

B-Pseudocumidine (1: 2: 4: 6) is formed when #-nitro- 
pseudocumene is reduced with iron filings and acetic acid. It 
is readily volatile with steam and solidifies in cooling to a 
crystalline mass, melting at 36°.3 

y-Pseudocumidine (1: 2: 4: 3) 1s contained in crude cumi- 
dine. When the fraction boiling at 225°—227° is boiled with 
glacial acetic acid for twelve hours, the acetyl-compound is 
formed, which, after being freed by pressure from the unattacked 
oil, is repeatedly crystallized from alcohol, a small quantity of 
acetmesidide being first deposited, while a compound is obtained 
from the mother-liquor, which boils at 112° and yields the 
new cumidine on distillation with caustic potash* This 
substance has also been prepared by the reduction of y-nitro- 
pseudocumene and is a liquid, boiling at 236° (Mayer). 

y-Nitropseudocumidine, C,A(CH3).(N O,)(NH,)(1 : 2: 4:3: 5), 
was obtained by Fittig and Laubinger, who reduced trinitro- 
pseudocumene with ammonium sulphide. Mayer found that 
when sulphuretted hydrogen is passed into a boiling solution of 


1 Auwers, Ber. Deutsch. Chem. Ges. xviii. 2661. 2 Haller, zbid. xviii. 89. 
3 Edler, ibid. xviii. 629. * Engler, <bid. xviii. 2229. 


MESITYL-COMPOUNDS. 121 


trinitropseudocumene in alcoholic ammonia, the acid C,H,,N,SO, 
is first formed. This compound is either a nitrocumidinesulphonic 
acid, C,(CH,),NO,(NH,)SO3H, or more probably nitrocumene- 
sulphamic acid, C,H(CH;),NO,(NH.SO,H), since, on heating 
with water to 180°, it decomposes quantitatively into sulphuric 
acid and y-nitropseudocumidine, which is best prepared from 
trinitropseudocumene in this manner. It crystallizes from 
boiling water or alcohol in splendid golden-yellow, lustrous 
needles, melting at 137°, and forms salts, which crystallize well 
and are difficultly soluble. 


y Nitro-acetcumidide,C,H(NO,)(CH;),N H(C,H,0), Melting-point. 


dull yellow needles .. . oe 131° 
y-Dinitro-acetcumidide, C,(NO,) (CH)NHC, H. ip 

colourless needles . . . .....- 204° 
y-Dinitropseudocumidine, sane Hy 

fine, yellow needles . . . ee ar ae 73° 


y-Dianridopseudocumene, C,H(CH,),(NH,),, was obtained by 
Meyer from y-nitropseudocumidine by reduction with tin and 
hydrochloric acid. It is readily soluble in benzene and separates 
on the addition of petroleum-spirit in compact needles, melting 
~ at 84°. Its hydrochloride produces a deep yellow colouration in 
a very dilute solution of sodium nitrite, while a brown precipitate 
is formed in a stronger solution. It forms chrysoidines with 
diazo-salts and therefore contains the amido-groups in the 
meta-position, this constitution being confirmed by its other 
reactions. 


MESITYL-COMPOUNDS. 
2336 Mesityl alcohol, C,H,(CH,),CH,.OH, has been prepared 


from its acetic ether and forms a liquid which has a similar 
smell to benzyl alcohol and boils at 218°—221°. 

Mesityl chloride, C,H,(CH;),CH,Cl, is formed when mesity- 
lene is chlorinated at a tolerably high temperature, which must 
not however exceed 215°, and is a liquid boiling at 215°—220°2 

Mesityl bromide, C,H,(CH,),CH,Br, is obtained by the action 
of bromine on mesitylene at 135°—140°, and crystallizes in long 


1 Ber. Deutsch. Chem. Ges. xx. 966. 
2 Robinet, Compt. Rend. xevi. 500. 


122 AROMATIC COMPOUNDS. 


needles or prisms, melting at 38°. It boils at 230° and yields 
a vapour, which produces a copious flow of tears." 

Mesityl acetate, C,H,(CH,),CH,.0O.C,H,O, is prepared by 
heating the chloride or bromide with potassium acetate and 
acetic acid. It forms a pleasant-smelling liquid, which, according 
to Wispek, boils at 228°—231°, but according to Robinet at 242°. 

Bromomesityl alcohol, C,H,Br(CH;),CH,OH. The bromide 
of this is formed by the action of bromine on bromomesitylene 
in the sunlight and is a liquid which decomposes on distillation. 
When it is boiled with an alcoholic solution of potassium acetate 
and the product decomposed with caustic potash, the alcohol is 
obtained. It crystallizes from petroleum-spirit in stellate groups 
of needles, which melt at 66°—66°5° and are oxidized to 
8-bromomesitylenic acid by potassium permanganate. It de- 
composes on distillation with formation of bromomesitylene, 
8-bromomesitylaldehyde, which rapidly oxidizes in the air, 
and other products. The main reaction is explained by the 
following equation :? 


2C,H,Br(CH,),CH,.OH = 
C,H,Br(CH,); + C,H,Br.CH,)CHO + H,0. 


DIMETHYLBENZENECARBOXYLIC ACIDS, 
C,H,(CH,),CO,H. 


2337 ‘The numbers appended give the positions of the side 
chains in the following order, CH, : CH, : CO,H. 

Mesitylence acid, (1:3: 5), was first prepared by Fittig. 
Mesitylene is boiled for 16—20 hours with nitric acid of sp. gr. 
14, to which two volumes of water have been added, and the 
product is then greatly diluted with water and submitted to 
distillation. Nitromesitylene passes over first and then the 
acid, the distillation being continued until crystals of this are no 
longer deposited in the condenser, water being added to the 
residue in the retort as often as is necessary. The acid is then 
filtered off and the filtrate saturated with sodium carbonate, 
evaporated to a small bulk, and precipitated with hydrochloric 
acid. The acid thus obtained is added to that remaining on the 
filter, which forms the larger portion, and the whole is boiled for 


1 Wispek, Ber. Deutsch. Chem. Ges. xvi. 1577. 
* Schramm, 7zbid. xix. 212. 


DIMETHYLBENZENECARBOXYLIC ACIDS. 123 





some time with tin and concentrated hydrochloric acid in order 
to remove any nitro-compounds. After cooling it is washed 
with water, dissolved in sodium carbonate and liberated by the 
addition of hydrochloric acid to the solution at the boiling-point. 
The pure mesitylenic acid separates out on cooling in dazzling 
white crystals.} 

Uvitic acid, C,H,(CH,)(CO,H),, is also a product of this 
reaction, but is not volatile with steam ; in order to isolate this, 
the filtered oxidation-product is separated from unattacked 
mesitylene and nitromesitylene by solution in sodium carbonate, 
the two acids precipitated from the filtrate with hydrochloric 
acid, treated with tin and hydrochloric acid and finally separated 
by distillation with water.” 

According to Remsen and Broun, it is better to employ a 
mixture of one volume of nitric acid of sp. gr. 1°35 with two 
volumes of water in this reaction.® 

Mesitylenic acid is also formed by the oxidation of mesity] 
alcohol, an oily liquid being obtained at the same time, which 
forms a crystalline compound with acid sodium sulphite, and is 
therefore probably mesitylaldehyde C,H,(CH,),CHO. 

Geuther and Frohlich found that small quantities of mesity- 
lenic acid are formed, together with butyric acid, diethylacetic 
acid and tri-ethenylbutyric acid, C,H,(C,H,),CO,H. when a 
mixture of sodium ethylate and sodium acetate is heated with 
carbon monoxide or zinc dust. 

Mesitylenic acid is only soluble to a very small extent in cold 
water and with difficulty in boiling water, from which it crystal- 
lizes in fine, small needles. It separates from alcohol, in which 
it is very readily soluble, in large, well-developed, monosymmetric 
crystals, while if boiling water be added to the dilute alcoholic 
solution until a permanent turbidity is produced, the acid 
crystallizes on cooling in broad plates and needles, which closely 
resemble those of benzoic acid. It melts at 166° according to 
Fittig,® while.Jacobsen gives 169° as the melting-point, but 
sublimes below this temperature. Its salts have been examined 
by Fittig and by Fittig and Briickner.’ 

Calcium mesitylenate, (CyH,O,),Ca, is scarcely more soluble in 
hot water than in cold and separates in crystalline crusts when 
the solution is evaporated. 


1 Ann. Chem. Pharm. exli. 144. 2 Fittig and paced ees ibid. exlvii. 295. 
3 Amer. Chem. Journ. iii. 216. ‘ Robinet, Compt. Rend. xevi. 500. 

5 Ann. Chem. Pharm. ccii. 305. 6 Ber. Deutsch Chem. Ges. xi. 2054. 

7 Ann. Chem. Pharm. exlvii. 45. 


124 AROMATIC COMPOUNDS. 


Barium mesitylenate, (C,H,O,),Ba, is more readily soluble in 
hot water than in cold and does not crystallize immediately 
when the boiling, saturated solution is allowed to cool, but 
only after standing for some hours; it forms prisms with a silky 
lustre. 

Ethyl mesitylenate, C,H,0,.C,H;, is formed by the action of 
hydrochloric acid on a solution of the acid in absolute alcohol, 
and is a liquid which has a peculiar, but pleasant, smell re- 
sembling that of attar of roses, boils at 241° and solidifies to a 
crystalline mass below 0°. 

Mesitylenamide, C,H,(CH,),CO.NH,. The acid chloride is 
formed by the action of phosphorus chloride on mesitylenic 
acid, but has not yet been prepared pure. It is converted by 
ammonia into the amide, which crystallizes from boiling water 
in needles, which melt at 133° and sublime at a slightly higher 
temperature (Fittig and engenee 

2338 Xylic acid, (1:3:4), was first prepared by Kekulé by 
the action of carbon dioxide and sodium on a-bromometaxylene.} 
It may also be obtained, together with paraxylic acid and 
xylidic acid, by the oxidation of pseudocumene with dilute 
nitric acid,? and is very readily formed when carbonyl chloride 
is passed into a mixture of metaxylene and aluminium chloride, 
- which is heated to 100° at intervals. The acid chloride is thus 
formed and is then decomposed with water, the product being 
subsequently distilled. Unattacked metaxylene passes over 
first and is followed by an oily liquid, boiling between 170° 
and 320°, which is extracted with caustic soda, the xylic 
acid being precipitated from the solution with hydrochloric 
acid and recrystallized from alcohol.2 It is also formed when 
the potassium salt of a-metaxylenesulphonic acid is fused with 
sodium formate.‘ 

Xylic acid is almost insoluble in cold and only slightly 
soluble in boiling water, and crystallizes from alcohol in 
well-formed, transparent, monosymmetric prisms, melting at 
126°. It boils at 267° under a pressure of 727 mm., and yields 
pure metaxylene when heated with lime at a comparatively low 
temperature. 

Calewwm aylate, (C,H,0,)Ca+2H,0, is readily soluble in water 

1 Ann. Chem. Pharm. cxxxvii. 186. 
ae pelanes Zeitschr. Chem. 1867, 12; 1868, 545; Fittig and Laubinger, <bid. 


3 Ador and Meier, Ber. Deutsch. Chem. Gies. xii. 1968. 
4 Jacobsen, zbid. xi. 18. 


XYLIC ACID. 125 





and crystallizes in hard, transparent, monosymmetric prisms, 
which only redissolve very slowly. 

Barium «xylate, (C,H,O,).Ba, crystallizes from a concentrated 
solution in hard, thick plates. 

Xylyl chloride, C,H,(CH,),COCI, is prepared by fusing the 
acid with phosphorus chloride; it boils at 234°—236°, and 
solidifies on cooling in fascicular groups of needles, melting 
at 25°5°. 

Xylamide, C,H3(CH,),CO.NH,, is obtained by triturating the 
chloride with ammonium carbonate. It crystallizes from hot 
water in fan-shaped groups of needles, and from alcohol in 
prismatic clusters of needles, melting at 181°. 

Paraxylic acud, (1: 2:4), is formed by the oxidation of pseudo- 
cumene and also when potassium orthoxylenesulphonate is fused 
with sodium formate (Jacobsen). In order to prepare it, 
pseudocumene is boiled for about a day with dilute nitric 
acid, distilled with steam and the distillate neutralized with 
carbonate of soda and freed from nitropseudocumene by distilla- 
tion. The residue is then heated with an excess of hydrochloric 
acid and tin, the acids converted into the calcium salts and these 
separated by crystallization. 

Paraxylic acid is scarcely soluble in water in the cold, and only 
dissolves to a small extent at the boiling-point; it is deposited 
from an alcoholic solution, which is allowed to evaporate spon- 
taneously, in concentrically-grouped prisms, melting at 166°. On 
distillation with lime it yields pure orthoxylene, which was 
discovered in this way. 

Caleiwm paraxylate, 2(CjH,O,),Ca + 7H,O, is less soluble 
in water than calcium xylate, and crystallizes in pointed, white 
needles, which however redissolve much more rapidly than those 
of the latter salt. 

Barium paraxylate, (Cj,H,O,),Ba + 4H,0, is less soluble in 
water than barium xylate and crystallizes in fascicular or stellate 
groups of hard needles. 

Isoxylic acid (1:4:2) was obtained by Jacobsen by heating 
bromoparaxylene with sodium amalgam and ethyl chlorocarbonate. 
It crystallizes from alcohol in stellate groups of large needles, 
melts at 132° and boils at 268°. 

Caleiwm <isoxylate, (CjH,O,),Ca + 2H,O, is scarcely more 
soluble in hot water than in cold, and separates on evaporation 
in tolerably hard, radiating crusts. 

Barium isoxylate, (CjH,O,),Ba + 4H,0, crystallizes slowly 


- 126 AROMATIC COMPOUNDS. 


from a concentrated solution in masses composed of small 
needles. 

Isoxylamide, C,H,(CH,),CO.NH,, has been prepared from the 
chloride, which crystallizes in the cold, by trituration with 
ammonium carbonate, and is deposited from hot water in long 
brittle needles, melting at 186°." 

w-Xylic acid (1:3:2) is formed when the potassium salt 
of v-metaxylenesulphonic acid is fused with sodium formate. 
It is more readily soluble in water than xylic and mesity- 
lenic acids, which also contain the methyl groups in the 
meta-position, and crystallizes in short needles, melting at 
97°—99°? 

Hemellithic acid (1:2:38) is obtained by the oxidation of 
hemellithene with dilute nitric acid. It is readly volatile with 
steam and crystallizes from hot alcohol in large, brittle, vitreous 
prisms, which melt at 144° and are only slightly soluble even in 
hot water. 

Calewwm hemellithate, (C,H,0,),Ca +, H,O, crystallizes from hot 
water in tufts of prisms and yields pure orthoxylene on distillation 
with lime. 


SUBSTITUTION PRODUCTS OF THE DIMETHYL- 
BENZENECARBOXYLIC ACIDS. 


2339 B-Chloromesitylenie acid, C,H,Cl(CH,),CC,H, is formed 
by the oxidation of chloromesitylene with dilute nitric acid. It 
is slightly soluble in hot water, readily in alcohol, from which it 
crystallizes in monosymmetric prisms, which become coloured 
brown at 220° without melting.? 

a-Bromomesitylenic acid, C,H,Br(CH,),CO,H, is the chief 
product of the action of bromine on mesitylenic acid in the 
cold, and has also been prepared from a-amidomesitylenic acid 
by means of the diazo-reaction. It crystallizes from hot water 
in fine needles, often an inch in length, and is deposited on the 
evaporation of its alcoholic solution in large, rhombic prisms, 
which melt at 146°—147°, solidify at 131° when gradually cooled, 
and then melt at 137°—138°. It resembles §-nitromesitylenic 


1 Ber. Deutsch. Chem. Ges. xiv. 2110. 2 Jacobsen, zbid, xi. 21. 
3 Fittig and Hoogewerff, Ann. Chem. Pharm. cl. 325. 


a-NITROMESITYLENIC ACID. 127 


acid in this respect, the lower melting substance being the mobile 
modification, the higher melting the stable.’ 

8-Bromomesitylenic acid is formed in small quantity together 
with the a-acid, and may also be obtained by the oxidation of 
bromomesitylene with chromic acid solution or dilute nitric acid.” 
In addition to these methods it has been prepared from 8-amido- 
mesitylenic acid (Schmitz). It separates from hot water, in which 
it is only slightly soluble, in compact crystals and from alcohol 
in well-developed, monosymmetric prisms, which have almost 
precisely the same form as §-nitromesitylenic acid and melt at 
214°—215°. 

a-Nitromesitylenie acid, C,H,(NO,)(CH,),CO,H, is formed as 
the chief product, together with the 8-compound, when mesity- 
lenic acid is brought into fuming nitric acid, the mixture of the 
two acids being soon deposited. They are converted into 
their barium salts, that of the @-acid crystallizing out almost 
completely when its hot solution is allowed to cool. The salt 
of the a-acid is obtained from the mother-liquor and is purified 
by recrystallization and decomposed with hydrochloric acid. 

a-Nitromesitylenic acid crystallizes from hot water, in which 
it is only slightly soluble, in long fine needles, and separates from 
an alcoholic solution in larger crystals, which form intersecting 
twins and melt at 210°—212° (Schmitz). 

B-Nitromesitylenie acid is also formed, together with nitro- 
mesitylene, in the preparation of mesitylenic acid (Fittig and 
Briickner), as well as by the oxidation of nitromesitylene with 
chromic acid.’ It is almost insoluble in cold, only very slightly 
soluble in boiling water and crystallizes from hot alcohol in well- 
developed monosymmetric prisms, which, according to Schmitz, 
commence to soften at 195°, but are not completely fused until 
the temperature reaches 220°5°. When gradually cooled the 
acid solidifies at 161°—162° and then melts completely at 
167°—168° ; if it be now further heated and a crystal of the acid 
added to the fused mass, it solidifies immediately and does not 
completely fuse again until the temperature is raised to 220°5°, 
It therefore exists in two modifications, one of which gradually 
changes into the other as the temperature is raised. Jacobsen 
found that the acid obtained by crystallization from hot water 
or alcohol, or by the evaporation of its solution in absolute 


1 Schmitz, Ann. Chem. Pharm. exciii. 160. 
2 Fittig and Storer, ibid. exlvii. 8. 
3 Emersen, Amer. Chem. Journ. viii. 268. 


128 AROMATIC COMPOUNDS. 


alcohol, melts at 179°, while it separates from hot absolute 
alcohol in crystals, which melt at 223° and are converted 
by hot water into the modification which has the lower melt- 
ing point. 

Nitroxylic acid, C,H,(NO,)(CH;),CO,H, was prepared by 
Schaper by the oxidation of mononitropseudocumene with 
chromic acid solution. It crystallizes in fine needles, which melt 
at 195° and are only slightly soluble in cold, more readily in 
boiling water and readily in alcohol.? 

2340 a-Amidomesitylenic acid, C,H,(NH,)(CH;),CO,H, is 
obtained by the reduction of the nitro-acid with tin and hydro- 
chloric acid. It crystallizes from hot water or alcohol in long 
needles, melting at 190°. On heating with lime, it decomposes 
into carbon dioxide and a-metaxylidine. 

B-Amidomesitylenic acid is only slightly soluble in water and 
crystallizes from hot alcohol in needles, melting at 235°. When 
heated with lime it yields v-metaxylidine. The constitution 
of the amidomesitylenic ca is therefore expressed by the 
following formulae : 


te Hl CO,H 

NH, 

CH i CH, On 
Ned Baa 


The constitution of nitromesitylenic acid and ee 
acid is also thus determined, and it follows from these, that when 
a substituted mesitylene is oxidized, the methyl group, which is 
in the para-position to the substituent, 1s converted into carboxyl, 
while when one of the hydrogen atoms in mesitylenic acid is 
replaced by bromine or nitroxyl, the latter take the ortho- 
position to the carboxy]. 

Sulphomesitylente acid, C,H,(SO,H)(CH,),CO.H, is formed by 
the action of sulphur trioxide on mesitylenic acid in’ two modi- 
fications, which can be separated by means of their calcium 
salts3 

a-Sulphamidomesitylenic acid, C,H,(SO,.NH,)(CH,),CO,H, is 
obtained, together with a small amount of the A-acid, by the 
oxidation of mesitylenesulphamide with chromic acid. It 


1 Jacobsen, Ber. Deutsch. Chem. Ges. xi. 2052. 
2 Zeitschr. Chem. 1867, 13. 
3 Remsen and Brown, Amer. Chem. Journ. iii. 218. 


SULPHAMIDOXYLIC ACID 129 





crystallizes from hot water or alcohol in short, compact prisms 
with a vitreous lustre, which melt at 263° and are converted by 
concentrated HCl at 200° into mesitylenic acid, which is also 
formed, together with a-metaxylenesulphamide, when the sulph- 
amic acid is fused with caustic soda. 

B-Sulphamidomesitylene acid is formed, together with about 
an equal quantity of the a-acid, by the oxidation of mesitylene- 
sulphamide with an alkaline solution of potassium permanganate. 
It crystallizes from hot water in long fine needles, which are 
readily soluble in alcohol and melt at 276° with decomposition. 
On heating with hydrochloric acid, it yields mesitylenic acid and 
is converted into @-hydroxymesitic acid by fusion with caustic 
soda (Jacobsen). 

The constitution of these two acids is expressed by the 
following formulae : 


CO,H CO,H 
@ 2 02H, (2) 
CH, CH, CHA /CH, 
So,.NH, 


Sulphamidoxylie acid, C,H,(CH,),(SO,.NH,)CO,H(1 : 3 : 4:6), 
is formed by the oxidation of pseudocumenesulphamide. It is 
almost insoluble in cold water and only slightly soluble in 
boiling water, from which it crystallizes in long, fine needles 
which melt at 260° and are converted into xylic acid by hydro- 
chloric acid at 210°. 

a-Sulphamidohemellithic acid (1:2:5:3) is obtained, accom- 
panied by the 8-compound, when hemellithenesulphamide is 
oxidized with potassium permanganate in faintly alkaline 
solution, and crystallizes from water in long, flat needles, melting 
at 238°. On heating to 150° with hydrochloric acid, hemellithic 
acid is formed. 

B-Sulphamidohemellithie acid (1:3:5:2) is more readily 
soluble than the a-acid and crystallizes in stellate groups of 
microscopic needles, which melt at 174°. An isomeric hemellitic 
acid is not formed on heating with hydrochloric acid, but decom- 
position into carbon dioxide and metaxylene takes place? 


1 Jacobsen and Meyer, Ber. Deutsch. Chem. Ges. xvi. 190. 
2 Jacobsen, zbid. xix. 2519. 


130 AROMATIC COMPOUNDS. 





DIMETHYLHYDROXYBENZENECARBOXYLIC 
ACIDS, C,H,(OH)(CH,),CO,H. 


2341 The numbers appended give the positions of the side 
chain in the order CH, : CH, : CO,H : OH. 

a-Hydroxymesitylenic acid (1:3:5:6) 1s formed by fusing 
mesitylenesulphonic acid with caustic potash,! mesitol being 
first formed and then undergoing oxidation.2 If the tempera- 
ture be rapidly raised until the poimt is reached at which 
the potassium salt of mesitol floats on the surface of the fused 
mass, this is almost the only product; while if the separa- 
tion of the potassium salt be prevented by constant agitation 
and the maintenance of a lower temperature, the mesitol is 
oxidized to hydroxymesitylenic acid as rapidly as it is formed. 

It may also be obtained by gradually adding potassium nitrite 
to a solution of a-amidomesitylenic acid in dilute sulphuric acid 
and distilling with steam.* It is, however, best prepared by the 
action of sodium and carbon dioxide on a-metaxylenol, which 
must be diluted with a hydrocarbon of high boiling point in 
order to prevent the solidification of the mixture.® 

It is slightly soluble in water, readily in alcohol ana crystallizes 
from dilute alcohol in long, flat needles, which melt at 179°, 
sublime readily and are volatile with steam. It corresponds to 
salicylic acid and its aqueous solution is coloured deep blue by 
ferric chloride. On heating with concentrated hydrochloric acid 
to 200°, or when rapidly fused with caustic potash at a high 
temperature, it decomposes into carbon dioxide and a-meta- 
xylenol. 

B-Hydroxymesitylenie acid (1: 3:5: 2) is readily formed when 
8-sulphamidomesitylenic acid is fused with potash.® It is also 
formed by the action of nitrous acid on 8-amidomesitylenic acid, 
and in small quantity, together with the a-acid, by the fusion of 
mesitylene with caustic potash (Jacobsen). 

It crystallizes from hot water, in which it is only slightly 
soluble, in long, hair-like, pliant needles and from alcohol in 
shorter compact needles, which melt at 223° and sublime when 


1 Fittig and Hoogueneff, Ann. Chem. Pharm. cl. 329. 

2 Jacobsen, ibid. cxev. 274. 3 Jacobsen, ibid. ecvi. 200. 
4 Jacobsen, Ber. Deutsch. Chem. Ges. xi. 2055. 

5 Jacobsen, ibid. xiv. 44. 6 Jacobsen, ibid. xii. 606. 


DIMETHYLHYDROXYBENZENECARBOXYLIC ACIDS. 131 





carefully heated above this temperature. It is not volatile 
with steam and gives no colouration with ferric chloride ; if the 
latter be added to a solution of the ammonium salt, however, a 
brown precipitate is formed, which is soluble in hot water and 
in an excess of ferric chloride. On heating to 200° with con- 
centrated hydrochloric acid, it decomposes into v-metaxylenol 
and carbon dioxide. 

Hydroxyparaxylie acid (1:2:4:5) is formed by the continued 
fusion of pseudocumene with caustic potash. It is almost in- 
soluble in cold water, only slightly soluble in boiling water, and 
crystallizes from the latter or dilute alcohol in feathery groups 
of needles, while it separates from stronger alcohol in very small 
prisms, which melt at 199° and sublime even below this temper- 
ature. It volatilizes slowly with steam and gives a deep bluish- 
violet colouration with ferric chloride. It is resolved into 
carbon dioxide and a-orthoxylenol by hydrochloric acid at 
220°—225°1 

Ayletic acid has been prepared by the action of carbon dioxide 
and sodium on crude xylenol. It forms crystals, melting at 155°, 
and gives a violet colouration with ferric chloride.? 


DIMETHYLDIHYDROXYBENZENECARBO- 
XYLIC ACIDS, C,H(OH),(CH,),CO,H. 


2342 Only one of these bodies has hitherto been prepared. 

Metaxylorcinolcarborylic acid (1:3:4:6:5) is formed when 
metaxylorcinol (Vol. III. Pt. IV. p. 402) is heated to 130° with 
a solution of sodium carbonate. It is only slightly soluble in 
water and crystallizes from dilute alcohol in prisms, which melt 
at 196° with evolution of carbon dioxide. It gives a deep blue 
colouration with ferric chloride, and therefore probably contains 
the hydroxyl in the ortho-position to the carboxyl group, a 
supposition which is favoured by the readiness with which 
it decomposes on heating. 


1 Reuter, Ber. Deutsch. Chem. Ges. xi. 30; Jacobsen, zbid, xii. 434. 
2 Wroblewsky, Zeitschr. Chem. 1868, 233. 
3 Kostanecki, Ber. Deutsch. Chem. Ges. xix. 2323, 


132 AROMATIC COMPOUNDS. 


MESITENE-COMPOUNDS. 


2343 Mesitene alcohol or Mesityleneglycol, C,H,(CH,)(CH,.OH),, 
is prepared by boiling its chloride for some time with water 
and lead carbonate. It is a viscid liquid, which has a bitter 
taste, boils with partial decomposition at 280°, is readily soluble 
in alcohol and dissolves in about 20 parts of water." 

Mesitene chloride, C,H,(CH,)(CH,Cl),, is formed, together 
with mesityl chloride, by the action of chlorine on heated mesi- 
tylene. It crystallizes in small plates or needles, melts at 41°5°, 
and boils at 260°—265°. 

Mesitene bromide, C,H;(CH;)(CH,Br),, is obtained by the 
action of bromine on mesitylene vapour, as well as of hydro- 
bromic acid on the glycol, and crystallizes in fine needles, which 
melt at 66°3°° and have a very pungent odour. 

Mesitene acetate, C,H,(CH,)(CH,.0.C,H,0),, is obtained by 
boiling the chloride with acetic acid and silver acetate as a 
colourless, almost odourless liquid, which has an unpleasant 
burning taste and boils at 244° under a pressure of 120 mm. 


PSEUDOCUMYLENE COMPOUNDS. 


2344 Pseudocumylene alcohol, C,H,(CH,)(CH,.OH), (1:2: 4). 
When pseudocumene is heated with bromine in the sunlight, 
pseudocumyl bromide, C,H.(CH,;),CH,Br, is the first product. It 
is a liquid, which is completely decomposed by distillation, and 
is converted by the further action of bromine into psewdocumylene 
bromide,’ C,H,(CH,)(CH,Br),, which is also formed when pseudo- 
cumene is acted upon by bromine at a temperature of 140°.4 
It crystallizes from ether or petroleum-spirit in flat, lustrous 
needles, melting at 975°. On boiling with a solution of 


1 Robinet and Colson, Compt. Rend. xevi. 1863. 
2 Robinet, bid. xevi. 500. 

3 Schramm, Ber. Deutsch. Chem. Ges. xix. 217. 
4 Hjelt and Gadd, ibid. xix. 867. 


MESITENE COMPOUNDS. _ 133 


sodium carbonate it is converted into the alcohol, which 
is only slightly soluble in ether, readily in water, and 
is oxidized by chromic acid to f-xylidic acid (Hjelt and 
Gadd). 


METHYLBENZENEDICARBOXYLIC ACIDS, 
CH,(CH)(CO,H),. 


2345 Uvitic aid, (1:3:5), was first prepared by Finkh by 
boiling pyroracemic or pyruvic acid, CH;.CO.CO,H, with baryta 
water Fittig and Furtenbach then found mesidic acid among 
the oxidation products of mesitylene and stated that it was most 
probably identical with uvitic acid,2 this being confirmed by 
Baeyer.2 The formation of uvitic acid from pyroracemic acid is 
not brought about by a simple reaction ; Finkh obtained oxalic 
acid and the syrupy uvitonic acid as by-products, the latter 
being, according to Bottinger, a badly characterized compound 
and probably impure. The latter chemist found that in addition 
to these substances, acetic acid, pyrotartaric acid and uvic acid, 
C,H,O,, are also formed. Since acetone is so readily converted 
into mesitylene with elimination of water, it was to be expected 
that pyroracemic acid would be converted by an analagous re- 
action into trimesic acid, C,H,(CO,H).,, but not a trace of this 
compound is formed.® Harrow subsequently proved that uvic 
acid is identical with the pyrotritaric acid, which is formed by 
the dry distillation of tartaric acid (Vol. III. Pt. II. p. 222), and 
which he prepared synthetically by converting sodium aceto- 
acetic ether by the action of iodine into diacetosuccinic ether, 
which yields the ether of uvic acid when boiled with dilute 
sulphuric acid : 


CH,—CO—CH—CO, . C,H, 


| 
CH,—CO—CH—CO, . C,H, 
CH,—CO—CH—CO, . C,H; 
| + CO, + C,H,0. 

Gis C—O 


1 Ann. Chem. Pharm. exxii. 182. 

2 Zeitschr. Chem. [2] iv. i. ; Ann. Chem. Pharm. exlvii. 292. 
3 Zeitschr. Chem. [2] iv. 119. 

4 Ann. Chem. Pharm. elxxii. 239 ; clxxxviii. 293. 

5 Fittig and Bottinger, Ber. Dewtsch. Chem. Ges. v. 956. 


134 AROMATIC COMPOUNDS. 


The formation of uvitic acid from pyroracemic acid is then 
explained by the following equation :? 


GH,-00—C0.H CO-00a 


| = 

CH,—CO—CO,H CH, 
CH,—CO—CH—CO,H 
| + 2CO, + 2H,0. 

00 Eigse (Oe (SEI 


Uvitic acid is converted into benzoic acid on fusion with caustic 
potash by a reaction which can be simply explained by means of 
the formula given above. 

At least four molecules of pyroracemic acid take part in the 
formation of uvitic acid : 


CH, CO—CO,H 
c0,H—Co br 
CH, CO—CO,H = 
bo bu, 
Cogs 
CH, 
(oH 
He b con + CHO—CO,H + CO, + 3H,0. 
60,4 


The glyoxylic acid, which is simultaneously formed, is decom- 
posed by the baryta into oxalic acid and glycolic acid. The 
latter has hitherto not been detected among the products of the 
reaction, but is undoubtedly contained in the so-called uvitonic 
acid. 

The preparation of uvitic acid from mesitylene has already 
been described in connection with mesitylenic acid. It 
is almost insoluble in cold water and only very slightly 
soluble in boiling water, from which it crystallizes in fascicular 


1 Ann. Chem. Pharm. cci. 1638. 


UVITIC ACID. 135 








groups of fine needles, while it separates from alcohol in indis- 
tinct groups of crystals, and is precipitated from the hot alco- 
holic solution by the addition of water as a crystalline powder. 
It melts at 286°—287° and sublimes at a higher temperature 
without blackening ; when a mixture of the calcium salt with 
half its weight of slaked lime is heated to the melting point of 
lead, metatoluic acid is formed.! Its salts are soluble in water 
and for the most part crystallize well. 

a-Nitro-uvitie acid, C,H,(NO,)CH,(CO,H),, is formed, together 
with a smaller quantity of the B-acid, when uvitic acid is 
nitrated, and crystallizes in needles or prisms, which melt at 
226°—227° and are only slightly soluble in hot water. 

8-Nitro-wvitic acid is very slightly soluble in cold, more 
readily in hot water and crystallizes in acute rhombohedra. 

a-Amido-uwiitie acid, C,H,(NH.,)CH,(CO,H),, crystallizes from 
alcohol in long, yellow needles ; its alcoholic solution has a blue 
fluorescence, 

8-Amido-uvitic acid forms long, light-yellow needles.? 

Sulpho-uvitre acid, C,H,(SO,H)CH,(CO,H),, is formed when 
sulphamido-uvitic acid is repeatedly evaporated with hydro- 
chloric acid, and crystallizes from water, which contains sulphuric 
acid, in small, compact needles (Jacobsen). 

Sulphamine-wvitre acid, C,H,(SO,.N H,)CH,(CO,H),, is formed 
by the oxidation of mesitylenesulphamide or of the two sulph- 
amidomesitylenic acids with potassium permanganate.® It is 
separated from its salts by the addition of acids as the an- 
hydride, in a similar manner to orthosulphamidobenzoic acid 
(Vol. III. Pt. IV. p. 268). This crystallizes from hot water in 
small prisms, which melt at 270°—272°. 

2346 a-Xylidic acid (2:1:4) is formed by the oxidation of 
pseudocumene, and therefore by that of xylic acid and paraxylic 
acid, with dilute nitric acid. It is liberated from its salts by 
acids as an amorphous voluminous mass, which is only very 
slightly soluble in boiling water and separates from the solution 
in semi-crystalline flocks, while it may be obtained in the form 
of granular, crystalline, warty masses by the evaporation of its 
alcoholic solution. It melts at 291° and sublimes in a slow 
current of carbon dioxide in small, hard needles. The salts do 
not crystallize well.* 


1 Bottinger and Ramsay, Ann. Chem. Pharm. clxvilii. 255, 

2 Bottinger, 7bid. clxxxix. 171. 

3 Hall and Remsen, Amer. Chem. Journ. ii. 1386; Jacobsen, Ann. Chem. 
Pharm. ccevi. 180. 4 Fittig and Laubinger, did. cli. 269, 


275 


136 AROMATIC COMPOUNDS. 


Sulphamidoxylidie acid, C,H,(CH,)(SO,.NH,)(CO,H),, is 
formed by the oxidation of: sulphamidoxylic acid with potas- 
slum permanganate. It is readily soluble in water and crystal- 
lizes in needles or prisms, which melt at 295°—300° with 
decomposition.? 

B-Xylidic acid (1:2:4) has been prepared by Jacobsen by 
the oxidation of isoxylic acid and crystallizes from hot water 
In microscopic needles, which melt between 320° and 330° and 
sublime in small crystals with a vitreous lustre.” 

The isoxylidie acid, which Senhofer prepared by fusing 
y-toluenedisulphonic acid with sodium formate, and the methyl- 
isophthalie acid, which is formed by the oxidation of paraxylyl- 
methylketone, (CH,),C,H,.CO.CH,, and of methylpropylacetyl- 
benzene, (CH,)(C,H,)C,H,.C.COH,, are probably identical with 
$-xylidic acid.4 


METHYLHYDROXYBENZENEDICARBOXYLIC 
ACIDS, C,H,(OH)(CH,)(CO,H).. 


2347 Di-orthohydroxywvitie acid (CH, : CO,H :CO,H : OH= 
1:3:5:4) is prepared by fusing mesitol or a-hydroxymesitylenic 
acid with caustic potash, and crystallizes from hot water in long 
needles, which become soft between 225°—235° and melt with 
decomposition. Its aqueous solution gives a fine cherry-red 
colouration with ferric chloride ; when it is heated with hydro- 
chloric acid to 200°, paracresol is formed.° 

Para-orthohydroayuvitie acid (1:3:5:2) is obtained by the 
action of nitrous acid on a-amido-uvitic acid,° and by fusing 
sulphamido-uvitic acid with caustic potash.’ It crystallizes 
from alcohol in needles, melting with decomposition at about 
280°, is very slightly soluble in water and gives a violet-red 
colouration with ferric chloride. Orthocresol is formed when it 
is heated with hydrochloric acid. 

Metahydryoxyuvitic acid (1:4:6:3). The ethyl ether of 
this acid is formed by the action of chloroform, chloral, or ethyl- 


1 Jacobsen and Mayer, Ber. Deutsch. Chem. Ges. xvi. 190. 

ane C7) ee oh eas Pe 3 Ann. Chem. Pharm. clxiv. 134. 
4 Claus, Ber. Deutsch. Chem. Ges. xviii. 1858 ; xix. 233. 

> Jacobsen, Ann. Chem. Pharm. excv. 285; ccvi. 198. 

6 Bottinger, ibid. clxxxix. 147. 

7 Jacobsen, ibid. cevi. 187 ; Remsen and Hall, Ann, Chem. Journ. ii. 187. 


MESITENYL COMPOUNDS. 137 


trichloracetate on sodium aceto-acetic ether in presence of 
sodium ethylate In order to prepare it, one part of sodium 
is dissolved in ten parts of acetic ether and chloroform gradually 
added to the solution : 


CH, CH, 
| | 
CO CH,cCO C=CH—C.OH 


| | | I 
CHNa + CHCl, + CHNa = C—CH—CH + 2NaCl+HCl+ H,0. 
| 


| | | 
CO Cr iO CO 


| | | | 
OC,H, OC,H, OC,H; OC,H, 


The product is boiled with caustic soda and the acid pre- 
cipitated with hydrochloric acid. It is difficulty soluble in cold, 
more readily in hot water and crystallizes in thin needles, which 
soften and decompose at 290°. It gives a reddish violet coloura- 
tion with ferric chloride and on heating with lime is resolved 
into carbon dioxide and metacresol. 

Homohydroxyisophthalic acid (1:2:4:6) is formed when 
8-sulphoxylidic acid is heated to 220° with hydrochloric acid ; 
it crystallizes from hot water in needles, which melt with de- 
composition at a few degrees above 270°. It gives no colouration 
with ferric chloride (Jacobsen). ; 

Hydroxyxylidie acid (1:3:6: 4) is obtained by fusing sulph- 
amidoxylidic acid with caustic potash. It is also only very 
slightly soluble in hot water and crystallizes from dilute alcohol 
in microscopic prisms, which melt at 285°—290°, decomposing 
simultaneously into carbon dioxide and paracresol. It gives an 
intense dark red colouration with ferric chloride (Jacobsen). 


MESITENYL COMPOUNDS. 


2348 Mesitenyl alcohol or mesityleneglycerol, C,H,(CH,.OH),, is 
obtained by boiling its bromide with lead carbonate and water. 
It is a thick liquid, which readily dissolves in water and has a 
bitter taste. 

Mesitenyl chloride, C,H,(CH,Cl),, is formed when the glycerol 
is heated with hydrochloric acid, as well as by the action of 


1 Oppenheim and Pfaff, Ber. Dewtsch. Chem. Ges. vii. 929 ; viii. 884 ; Oppen- 
heim and Precht, zbid. ix. 321. 


138 AROMATIC COMPOUNDS. 


chlorine on the vapour of mesitylene. It boils with decom- 
position at 277°—284°, but distils under diminished pressure 
without change. 

Mesitenyl bromide, C,H,(CH,Br)s, is formed by the addition 
of the calculated quantity of bromine to boiling mesitylene and 
crystallizes from alcohol in long, microscopic needles, which melt 
at 945° 


BENZENETRICARBOXYLIC ACIDS, C,H,(CO,H),. 


2349 Trimesic acid (1:3:5) was first obtained in small 
quantity by Fittig, together with a large amount of acetic acid, 
by boiling mesitylene with a solution of potassium dichromate in 
dilute sulphuric acid. A better yield is obtained by the oxida- 
tion of mesitylenic acid, the boiling being discontinued as soon 
as the latter has disappeared from the surface of the liquid.? 
It is formed in the same way from uvitic acid? and s-triethyl- 
benzene,* and may also be obtained by heating hydromellitic 
acid with sulphuric acid :° 


C,H,(CO,H), + 380,H, = 
C.H,(CO,H), + 8CO, + 6H,O + 380,. 


In addition to these methods it may be prepared by heat- 
ing mellithic acid, C,(CO,H),, with glycerol,® and in smaller 
quantity when sodium metabromosulphobenzoate is fused with 
sodium formate.’ 7 

When propargylic acid, CH=C.CO,H, is exposed to sun- 
light, it is gradually converted into trimesic acid.§ This poly- 
merisation corresponds exactly to the formation of benzene from 
acetylene and to that of s-tribromobenzene from bromacetylene, 
which is also brought about by exposure to sunlight.® 

Trimesic acid is somewhat soluble in cold, more readily 


1 Colson, Compt. Rend. xcvi. 71 ; xcvii. 177. 

2 Ann. Chem. Pharm. exli. 142. 

3 Fittig and Furtenbach, zbid. cxlvii. 301 ; Baeyer, Zedtschr. Chem. 1868, 119. 

4 Jacobsen, Ber. Deutsch. Chem. Ges. vii. 1485; Friedel and Balsohn, Budi. 
Soc. Chim. xxxiv. 636. 

5 Baeyer, Ann. Chem. Pharm. Suppl. vii. 40 and 48, 

6 Baeyer, Ann. Chem. Pharm, elxvi. 340. 

7 Bottinger, Ber. Deutsch. Chem. Ges. vii. 1781. 

8 Baeyer, ibid, xix. 2185. 

9 Ssabanejew, zbid. xviii. Ref. 374. 





TRIMESIC ACID. 139 








in hot water, and crystallizes in hard, transparent, thick prisms, 
which melt above 300°, but sublime at lower temperature. 

Normal sodium trimesate, Cy7H,0,Na,, forms an indistinct 
crystalline mass, which is very slightly soluble in water and 
almost absolutely insoluble in alcohol. 

Acid sodiwm trimesate, CJH,O,Na, is a very characteristic 
salt, crystallizing from hot water in splendid, lustrous plates, 
which are less soluble in cold water than the free acid. 

Normal barium trimesate, (C,H,0,),Ba, + H,O, separates on 
the addition of barium chloride to the ammoniacal solution of 
the acid as a semi-solid mass, consisting of lustrous needles. 
It is scarcely soluble in cold, only very slightly in boiling water, 
from which it crystallizes, after standing for some time in the 
cold, in lustrous needles. 

Acid barium trimesate, (C,H,O,),Ba + 4H,O, separates in hair- 
like, lustrous needles, when barium chloride is added to a hot 
aqueous solution of the acid. 

Methyl trimesate, C,H,0,(CH,)s, 1s readily formed by the 
action of methyl iodide on the silver salt, and forms small silky 
needles, melting at 143°. 

ithyl trimesate, C,H,0,(C,H,)3, crystallizes from alcohol in 
long, silky needles, which, according to Fittig and Furtenbach, 
melt at 129°, while Piutti gives the melting-point as 133°. The 
latter prepared this ether synthetically by the action of sodium 
on a mixture of ethyl formate and ethyl acetate while by re- 
placing the former by the methyl ether or the latter by methyl 
acetate, he obtained a mixture of ethyl and methyl trimesate, 
from which it follows that in the synthesis of the ethyl ether, 
the ethers of formylacetic acid, CHO.CH,.CO,.C,H,, and pyro- 
racemic acid, CH,.CO.CO,C,H,, are simultaneously formed, three 
molecules then condensing to ethyl trimesate with elimination 
of water. 7 

Sulphamidotrimesic acid, C,H,(SO,.NH,)(CO,H)., is formed 
by the further oxidation of sulphamido-uvitic acid, and forms 
an acid potassium salt, C,H,NSO,K + H,O, which separates 
from hot water as a fibrous crystalline mass and is converted 
into acid potassium trimesate by heating to 210°—220° with 
concentrated hydrochloric acid. (Jacobsen.) 

2350 Trimellithic acid (1:2:4) was first obtained by Baeyer, 
together with isophthalic acid and pyromellithic anhydride, by 
heating hydropyromellithic acid, C,H,(CO,H),, with sulphuric 

1 Ber. Deutsch. Chem. Ges, xx. 537. 


140 AROMATIC COMPOUNDS. 


acid.t It is also formed by the oxidation of a-xylidic acid with 
potassium permanganate,’ and by the fusion of the potassium 
salt of a-sulphophthalic acid with sodium formate.’ It can also 
be obtained by means of the diazo-reaction from amidotere- 
phthalic acid, the diazo-salt of which is converted into cyano- 
terephthalic acid by the action of a boiling solution of cuprous 
potassium cyanide, the trimellithic acid being prepared from 
this by boiling with caustic potash.* It is best obtained by the 
oxidation of colophony, which gives a yield of about 6 per 
cent. For this purpose, 100 grms. of the resin are boiled 
with two litres of a mixture of one volume of concentrated 
commercial nitric acid and two of water in a large retort for 
6—8 hours, until all frothimg has ceased; a fresh quantity of 
resin is then added and the process repeated, the alternate 
addition of colophony and nitric acid being continued until 
about one kilogr. of the former has been employed, the time 
occupied by this being about two weeks. The liquid is subse- 
quently distilled until the residue commences to froth and is 
then poured into ten volumes of cold water, filtered after twenty- 
four hours and evaporated to a thin syrup, which deposits a 
mixture of isophthalic and trimellithic acids after standing for 
some days. This is filtered off, drained by a filter pump and 
separated by recrystallization from hot water. 

Trimellithic acid is tolerably soluble in water, from which it 
separates in warty crusts, which melt at 216° and simultaneously 
decompose into water and the anhydride, which solidifies on 
cooling to a crystalline mass, melting at 157°—158°, and has the 
following constitution : 


aan 
C,H, 
008 OH. 


Larium trimellithate, (C,H,0,),Ba, + 4H,0, forms warty 
crystals, which are not readily soluble in water. 

Hemimellithic acid (1 :2:3) is obtained, together with phthalic 
anhydride, by heating hydromellophanic acid, C,H,(CO,H),, with 
sulphuric acid. It crystallizes in needles which are only slightly 
soluble in cold water, from which they are precipitated by 


1 Ann. Chem..Pharm. Suppl. vii. 40. 
2 Krinos, Ber Deutsch. Chem. Ges. x. 1494. 
3 Rée, Inauguraldiss, Bern 1886 ; Ann. Chem. Pharm. ccxxxiili. 230. 
‘ Ahrens, Ber. Deutsch. Chem. Gees. xix. 1634. 
> Schreder, Ann. Chem. Pharm. clxxii. 93. 


HEMIMELLITHIC ACID. 141 


hydrochloric acid. It decomposes on heating, with formation 
of phthalic anhydride and benzoic acid. 

Barium hemimellithate, (C5H,0,),Ba, + 5H,O, crystallizes in 
short, compact needles.! 


HYDROXYBENZENE-ALDEHYDO- 


/L00H 
DICARBOXYLIC ACIDS, 0,H,(OH)< CHO 
\CO.OH. 


2351 Aldehydo-a-hydroxyisophthalie acid, (CO,H :CO,H: CHO 
:OH=1:3:5:4), 1s obtained, together with paraldehydosalicylic 
acid (Vol. III. Pt. IV. p. 491), by heating a-hydroxyisophthalic 
acid with caustic potash and chloroform. It crystallizes from 
hot water in matted needles, which melt at 260° with vigorous 
evolution of gas. It gives a blood-red colouration with ferric 
chloride. Its neutral solution is colourless, while its alkaline 
solution is yellow, and both show a green fluorescence. 

Aldehydo-v-hydroxyisophthalic acid, (1:3: 5:2), is prepared in 
a similar manner from v-hydroxyisophthalic acid, and crystallizes 
in fine, long needles, which melt with decomposition at 237°— 
238°. It gives a cherry-red colouration with ferric chloride, 
resembling that of v-hydroxyisophthalic acid, and its solutions 
show the same blue fluorescence. It dissolves in alkalis without 
any yellow colouration.” 


HYDROXYBENZENETRICARBOXYLIC ACIDS, 
C,H,(OH)(CO_H);. 


2352 Hydroxytrimesic acid is formed by heating basic sodium 
salicylate or sodium phenate in a current of carbon dioxide to 
360°, as well as by fusing sulphamidotrimesic acid with potash, 
and by the oxidation of the two aldehydohydroxyisophthalic 
acids. It is slightly soluble in cold, more readily in hot 
water, and crystallizes from a concentrated solution in in- 


1 Baeyer, Ann. Chem. Pharm. Suppl. vii. 81; see also ibid. clxvi. 337. 
2 Reimer, Ber. Deutsch. Chem. Ges. xi. 793. 
3 Jacobsen, Ann. Chem. Pharm. ccvi. 167. 


142 AROMATIC COMPOUNDS. 








distinct prisms or needles, which contain one molecule of water 
and are united to crusts or warty masses, while it separates 
from dilute alcohol in fine, long, silky needles, containing 
two molecules of water. It gives a reddish brown colouration 
with ferric chloride. When it is heated above 100°, it de- 
composes into carbon dioxide, a-hydroxyisophthalic acid, salicylic 
acid and phenol. 

Acid calcium hydroxytrimesate, (CjH,O,),Cu + 6H,O, is ob- 
tained by the addition of calcium chloride to a hot solution of 
the acid and separates on cooling in splendid, long needles. 

Normal calcium hydroxytrimesate, (C>H,0,),Ca, + 8H,O, is a 
white precipitate, which is formed by the addition of calcium 
chloride to a solution of the acid neutralized by ammonia. It 
becomes anhydrous at 180° and then dissolves with tolerable 
readiness in cold water, but soon separates out, more rapidly on 
heating, in broad, hydrated needles. 

Bariumhydroaytrimesate, (C)H,0,),Ba, + 8H,O, is a precipitate, 
which is almost insoluble in hot water. 

Ethyl hydroxytrimesate, CjH,0,(C,H,;)s, is very readily formed 
when hydrochloric acid is passed into a solution of the acid in 
absolute alcohol and crystallizes in prisms an inch in length, which 
melt at 84°. When alcoholic caustic soda is added to its alcoholic 
solution, the compound C,H,(ONa)(CO,.C,H;), separates out 
in small needles, which rapidly change into oblique prisms. 
These gradually dissolve when boiled with water, sodiwm diethyl 
hydroxytrimesate, C,H,(OH)(CO,.C,H,;),CO,Na + H,O, being de- 
posited in hair-like needles on cooling. Free diethyl hydroxy- 
trumesic acid may be prepared from this by means of hydrochloric 
acid, and crystallizes in broad needles, containing one molecule 
of water, which is lost at 100°; the anhydrous compound melts 
at 148° (Ost.) 

Chlorotrimeste acid, C,H,Cl(CO,H), + H,O. When hydroxy- 
trimesic acid is distilled with phosphorus pentachloride, the 
chloride C,H,Cl(COC]), is obtained as an oily liquid, which is 
converted into the acid by heating with water. This crystallizes 
from hot water in stellate groups of thick needles, or acute- 
angled tablets, melts at 278° and sublimes, a small amount of 
hydrochloric acid being simultaneously formed. It gives a 
yellowish brown precipitate with ferric chloride and is con- 
verted into trimesic acid by the action of sodium amalgam and 
water. 

Barium chlorotrimesate, (Cy5H,C1O,),Bas + 7H,O, is tolerably 


a ae 


PHLOROGLUCINOLTRICARBOXYLIC ACID. 143 


soluble in cold water and is deposited on heating in matted 
needles, which redissolve as the solution cools.! 

Hydréxytrimellithie acid, (CO,H:CO,H:CO,H: OH=—1: 2: 
4:5) is prepared by fusing sulphamidotrimellithic acid with 
caustic potash, and crystallizes from alcohol in transparent, 
compact prisms, but from hot water in smaller, lustrous prisms, 
containmg two molecules of water, which they lose when 
heated, the anhydrous compound melting with decomposition 
at 240°—245°, It gives a deep brownish red colouration with 
ferric chloride and decomposes into carbon dioxide and meta- 
hydroxybenzoic acid when heated to 230°—240° with hydrochloric 
acid,” 


PHLOROGLUCINOLTRICARBOXYLIC ACID, 
C,(OH),(CO,H),. 


2353 The ethyl ether of this acid, which may also be termed 
trihydroxytrimesie acid, is formed when one atom of sodium is 
dissolved in two molecules of ethyl malonate and the mixture 
gradually heated to 145°.% The sodmalonic ether, which is 
the first product, probably decomposes into sodium ethylate 
and the residue CO.CH.CO.OC,H;, three of which then 
combine. 

The same compound is formed when a mixture of ethyl 
malonate and zinc methyl is heated and the product, which 
probably has the composition CH(ZnCH,)(CO.OC,H,),, warmed 
with hydrochloric acid, which decomposes it into zine chloride, 
methane, alcohol and CO.CH.CO.OC,H,.4 

Ethyl phloroglucinoltricarboxylate is only slightly soluble in 
alcohol and crystallizes in short, yellowish, lustrous needles, 
which melt at 104° and form a solution in ether which possesses 
a green fluorescence. On fusion with caustic potash it yields 
pure phloroglucinol.° 

It shows a great similarity to succinylsuccinic ether and 
its constitution, like that of the latter and of phlorglucinol 


1 Ost, Journ. prakt. Chem. [2] xv. 308. 

2 Ber. Deutsch. Chem. Ges. xvi. 192. 

3 Baeyer, ibid. xviii. 3454. 

4 Lang, bid. xix. 2937. 

5 This melts at 217°-218°; see also zbid. xix. 2186, 


144 AROMATIC COMPOUNDS. 


itself, can be expressed by two tautomeric formule (Pt, IV. 
p. 518). 

CO,.C,H, 

| 


C 
HOC” \COH 


| | 
C,H,CO—Cy C—00,,0,H, 
GOH 
CO,.C,H, 


CH 
oc% \co 


| | 
C,H,CO,-HO. /CH—0O,0,H, 
GO 


ds 
THE METHYLETHYLBENZENES, CoH : 
C,H, 


2354 Paramethylethylbenzene, or Ethyltoluene, is formed by the 
action of sodium on a mixture of parabromotoluene and ethyl 
bromide or iodide ;* it is a liquid, which does not solidify in a 
freezing mixture and boils at 161°—162°. It is oxidized by 
dilute nitric acid to paratoluic acid. On bromination it yields 
bromo-ethyltoluene, which is converted into parabromotoluic acid 
on oxidation.2 Fuming nitric acid converts it into two dinitro- 
methylethylbenzenes, C,H,(NO,),CH.(C,H;), one of which crys- 
tallizes in compact monosymmetric prisms or large tablets, 
melting at 52°, while the other does not solidify even in a 
freezing mixture. A mixture of nitric and sulphuric acids 
converts both into trinitromethylethylbenzene, C,H(NO,),CH, 
(C,H,), which crystallizes from boiling alcohol in stellate groups 
of short, hard prisms, melting at 92°. 

Metamethylethylbenzene has been prepared from metabromo- 
toluene and ethylbromide,? and is also formed, together with 


1 Fittig and Glinzer, Ann. Chem. Pharm. exxxvi. 312; Jannasch and Dieck- 
mann, Ler. Deutsch. Chem. Ges. vii. 1513. 

2 Morse and Remsen, Ber. Deutsch. Chem. Ges. xi. 224. 

3 Wroblewsky, Ann. Chem. Pharm. excii. 196. 


2 — 


TOLYLMETHYLKETONES. 145 





toluene and other hydrocarbons, when abietic acid, the chief 
constituent of pine resin, is distilled with zinc dust.’ It is a 
liquid, which boils at 158°—159°, and is oxidized to isophthalic 
acid by chromic acid solution. 

Orthomethylethylbenzene is formed by the action of sodium on 
a mixture of orthobromotoluene and ethyl bromide and is a 
liquid, which boils at 160° and is oxidized to orthotoluic acid by 
nitric acid.2 This is: also formed, together with phthalic acid, 
when the hydrocarbon is oxidized in the cold with potassium 
permanganate, but the chief product is terephthalic acid, which 
is not formed at a higher temperature, since complete combustion 
then takes place.*? This remarkable formation of terephthalic 
acid is probably analogous to that of benzoic acid by the 
oxidation of benzene (Pt. III. p. 76). When the hydro- 
carbon is brominated in the cold, bromorthomethylethylbenzene, 
C,H,Br(CH,)C,H,, is formed as a liquid, boiling at 220°—221°. 

Amidomethylethylbenzene, C,H(NH,)(CH;)C,H,, is formed by 
heating orthotoluidine with ethyl alcohol and zine chloride to 
260°—280°. Itis an oily liquid, which has an aromatic odour, 
boils at 229°—230° and gives the carbamine reaction. It is 
not known from which of the methylethylbenzenes it is 
derived.* 


CH 
TOLYLMETHYLKETONES, C,H, ae 
CO.CH, 


2355 Paratolylmethylketone was first prepared by Michaelis, 
who heated toluene with acetic anhydride and a little aluminium 
chloride. A better yield is obtained when aluminium chloride 
is suspended in carbon disulphide and a mixture of acetyl 
chloride and toluene gradually added at the ordinary temperature 
with constant agitation.® 

It is also formed, accompanied by smaller quantities of nitro- 
products, by the action of nitric acid on cymene, CH,.C,H,.C,H,,7 
and is a liquid, which has a pleasant odour, melts at 220° and is 
oxidized to paratoluic acid by dilute nitric acid and to terephthalic 
acid by potassium permanganate. 

1 Ciamician, Ber. Deutsch. Chem. Ges. xi. 269. 
2 Claus and Mann, 7bid. xviii. 1121. 3 Claus and Pieszcek, zbid. xix. 3083. 


4 Benz, ibid. xv. 1646. 5 Ibid. xv. 185. 
6 Claus and Riedel, zbid. xix. 234. 7 Bladin and Widman, ibid. xix. 584. 


(146 AROMATIC COMPOUNDS. 


Methyltolylacetoxime, CH,.C,H,C(NOH)CH,, is scarcely 
soluble in water, readily in alcohol and separates from hot 
petroleum-ether in short, lustrous crystals, melting at 88°. 

Methyltolylketonephenylhydrazine, CH3.C,H,.C(N,H.C,H;)CH, 
crystallizes from alcohol in lustrous prisms, melting at 97°, which 
rapidly change in the air into a brown liquid (Bladin and 
Widmann). 

Metatolylmethylketone is formed, according to Essner and 
Gossin, when acetyl chloride and aluminium chloride are 
eradually added to a mixture of toluene with a little aluminium 
chloride. It is a liquid, which has an aromatic odour, boils at 
224°—225° and is converted by oxidation with potassium per- 
manganate into isophthalic acid. On heating with alcoholic 
potash, it decomposes into acetic acid and toluene. Its 
isomerides are also present in the crude product, since small 
quantities of phthalic and terephthalic acids are formed when 
this is oxidized.t 


ETHYLBENZENECARBOXYLIC ACIDS OR 
ETHYLPHENYLFORMIC ACIDS, 
C,H 
CH sais 
CO,H 


2356 Para-ethylbenzenecarboxylic acid is formed by the oxida- 
tion of paradiethylbenzene with nitric acid,? and by the action of 
sodium and carbon dioxide on parabromethylbenzene? It 
crystallizes from hot water in lustrous plates and from alcohol 
in small prisms, which melt at 110°—111°, sublime at a lower 
temperature and are converted into terephthalic acid by 
oxidation. 

Ortho-ethylbenzenecarboxylic acid is obtained when _ ortho- 
acetylbenzenecarboxylic acid, CH,.CO.C,H,.CO,H, is heated to 
180° with amorphous phosphorus and hydriodic acid, and may 
be oe in a similar manner from phthalylacetic acid : 


CO. CH,.CH, 
HK CH.CO,H + 4H = OH ele), 


4 
\cO0.0H 
1 Bull. Soc. Chim. xlii. 95. 


2 Fittig and Konig, Ann. Chem. Pharm. exliv. 290. 
3 Kekulé and Thorpe, Ber. Deutsch. Chem. Gres. ii. 421. 


METHYLSTYROLENE. 147, 





When water is added to its hot alcoholic solution, it is pre- 
cipitated in oily drops, which rapidly solidify to scales or plates 
resembling those of benzoic acid, while it 8 eae from hot 
water in flat, lustrous needles, melting at 68°.7 

Ethylhydroaybenzenecarboaylic acid, C.H,(OH)(C,H,)CO,H, 
was obtained by Beilstein and Kuhlberg by the action of carbon 
dioxide and sodium on a-ethylphenol (p. 4). It melts at 118°— 
120°, and gives a violet cclouration with ferric chloride.’ 


ye 
METHYLPHENYLACETIC ACIDS, C,H 


*\GH,,.CO,H 


Paramethylphenylacetic acid was obtained by Cannizzaro from 
paraxylyl chloride, by heating this with potassium eyanide and 
decomposing the nitril with caustic potash; he did not however 
publish any account of its properties? Radziszewski and 
Wispek then prepared it from paraxylyl bromide.* It is also 
formed when paratoluylcarboxylic acid is treated with hot water, 
iodine and red phosphorus and crystallizes in lustrous plates or 
needles, melting at 89°. 

Metamethylphenylacetic acid was prepared by Vollrath, who 
named it a-xylic acid, from the crude chloride of coal-tar xylene.® 
Radziszewski and Wispek then obtained it from pure metaxylyl 
bromide. It crystallizes from hot water in broad, satin lustrous 
needles, melting at 53°—54°. 

Orthomethylphenylacetie acid was also prepared by these 
chemists ; it forms long, silky needles, melting at 86°. 


METHYLSTYROLENE OR TOLYLETHYLENE, 
CH,.C,H,.CH — CH,. 


2357 This hydrocarbon is formed when metamethylcinnamic 
acid, CH,.C,H,.CH — CH.CO,H, is allowed to stand in contact 
with concentrated hydrobromic acid at the ordinary temperature, 
the product being then treated with water and sodium carbonate. 


1 Gabriel and Michael, Ber. Dewtsch. Chet. Ges. x. 2206 ; Zincke and Frohlich, 
ébid. xx. 1056. 2 Ann, Chem. Pharhi. elvi. 213. 

3 Ibid. exxiv. 252. 4 Ber. Deutsch. Chem. Ges. xv. 1748. 

5 Zeitschr. Chem. 1868, 489. 


148 AROMATIC COMPOUNDS. 








It is a liquid, which boils at 164° and, hke styrolene, changes 
into a polymeric modification when preserved. 

Methylstyrolene bromide, CH,.C,H,.CHBr.CH,Br, forms crystals, 
melting at 45°. On boiling with alcoholic potash it is converted 
into methyl-8-bromostyrolene, CH,.C,H,.CBr—CH,, a liquid 
which has an unpleasant odour and decomposes when heated. 
The isomeric methyl-a-bromostyrolene, CH3.C,H,.CH — CHBr, is 
formed by the action of bromine on an aqueous solution of sodium 
methylcinnamate as an oily, pleasant smelling liquid, which boils 
at 242°1 


METHYLPHENYL-HYDROXYACETIC ACIDS, 
CH, 


C,H 
*“\\GH(OH).COOH. 


Metamethylmandelic acid. The nitril of this acid is formed 
when hydrochloric acid is added to an ethereal solution of 
metatolualdehyde in which powdered potassium cyanide is 
suspended. It is an oily liquid, which is converted into the 
acid by heating to 60°—70° with fuming hydrochloric acid ; 
this is readily soluble in water and alcohol and crystallizes from 
benzene in lustrous plates, melting at 84°” 

Paramethylmandelic acid is formed by the action of water and 
sodium amalgam on paratoluylcarboxylic acid and crystallizes 
from hot water in large tablets, melting at 145°—146°.8 


KETONIC ACIDS, C,H,0.. 


2358 Para-acetylbenzote acid, C,H,(CO.CH,)CO,H, is formed 
together with terephthalic acid, when hydroxyisopropylbenzoic 
acid, (CH,),C(OH)C,H,.CO,H, is oxidized with chromic acid 
solution. It is only very slightly soluble in boiling water and 
crystallizes in lustrous needles, which melt at 200° and sublime 
at a higher temperature.* 


1 Miiller, Ber. Deutsch. Chem. Ges. xx. 1212. 

2? Bornemann, <bid. 

3 Claus and Kroseberg, bid. xx. 2048. 

4 R. Meyer, zbid. xii. 1071; Ann. Chem. Pharm. cexix. 259. 


ORTHO-ACETYLBENZOIC ACID. 149 


Ortho-acetylbenzote acid or Acetophenonecarboxylic acid. When 
phthalic anhydride is heated with acetic anhydride and sodium 
acetate, phthalylacetic acid is formed and is converted by alkalis 
into benzoylacetocarboxylic acid. This decomposes on boiling 
with water into carbon dioxide and ortho-acetylbenzoic acid : 


CO,H ott 
CHER = CHK + CO,. 
\CO0.CH,.CO,H CO.CH, 


It is also formed when phthalylacetic acid is heated to 200° 
with water : 


0 CO.OH 
eee ECO «HO CHO? CO.. 
Ce aa att + Hy, 6 ‘\\co.CH, + UY» 


It is deposited, when its solution in hot water is allowed to 
cool, in fine globules, which solidify to groups of crystals possess- 
ing a vitreous lustre, which melt at 114°—115° and have a sweet 
taste.! 

When sodium amalgam is added to its alkaline solution, it is 
converted into hydro-acetophenonecarboxylic acid, which, however 
immediately decomposes into a-methylphthalide and water when 
it is liberated by hydrochloric acid (Supt. IV. p. 442) : 


CH(OH)CH, OUCH, 
C = CHK >0 + H,0. 
co 


H 
Pale <ag OH 


The latter substance is an oily liquid, which solidifies below 0° 
and boils at 275°—276.° 

Orthotrichloracetylbenzore acid, C,H,(CO.CCl;)CO,H, is formed 
when the acid is suspended in warm acetic acid and treated 
with chlorine. It crystallizes from a large quantity of hot water 
in long needles, melting at 144°, and is decomposed by alkalis 
into chloroform and phthalic acid. 

Orthotribromacetylbenzore acid, C,H,(CO.CBr,)CO,H, is obtained 
in a similar manner to the chlorine compound and also forms 
long needles, melting at 159°5°—160°, which undergo a similar 
decomposition with alkalis. 

Paratoluylearboaylic acid, CH,.C,H,.CO.CO,H, is formed by 


1 Gabriel and Michael, Ber, Deutsch. Chem. Ges. x. 1551. 
2 Gabriel, dbid. xx. 2500. 


150 AROMATIC COMPOUNDS. 


the action of aluminium chloride on a mixture of toluene and 


amyloxalyl chloride: 
CH, | 
C,H;.CH, + COCI1.CO.OC,H,, = C TS + HCl. 
CO.CO.OC,H,, 


The product is decomposed with alcoholic potash and the acid 
liberated by hydrochloric acid.t It is also formed by the oxida- 
tion of paratolylmethylketone with an alkaline solution of 
potassium ferricyanide.” It crystallizes from petroleum-ether in 
large flat needles, which decompose on preservation after a few 
days, are readily soluble in water, soften at 80° and become com- 
pletely liquid at 99°. It is oxidized to paratoluic acid by 
potassium permanganate. If it be dissolved in sulphuric acid 
and treated with benzene which contains thiophene, the liquid 
becomes deep red, changing to blue-violet, and on the addition 
of water and evaporation of the benzene deposits the indophenin 
(p. 68), which has been formed, as a red powder, which is readily 
soluble in alcohol and dyes silk pink, 


OH 
HOMOPHTHALIC ACIDS, CHC 
CH,.CO,H. 


2359 Homo-orthophthalic acid. Hlasiwetz and Barth obtained 
isuvitie acid® by fusing the resin contained in gamboge with 
caustic potash, and W. Wislicenus found that benzyleyanide- 
orthocarboxylic acid is formed when phthalide is heated with 
potassium cyanide : 4 


Eh; CH,.CN 
H,c# Bids O14 cK GNEESG, Feat Tate 
<i 0% \c0.0K 


It separates from a hot solution in acetic acid as a yellowish 
sandy power, which after purification becomes white and indis- 
tinctly crystalline, and is converted by boiling with caustic 
potash into phenylacetorthocarboxylic acid or homo-ortho- 
phthalic acid, which has been shown by Schuder to be identical 


1 Roser, Ber. Deutsch. Chem. Ges. xiv. 1750. 

2 Buchka aud Irisch, 7bid. xx. 1762. 

3 Ann. Chem. Pharm: CXXXVili. 68. 

4 Ber. Deutsch. Chem. Ges. xviii. 172; Ann. Chem. Pharm. ecxxxili, 10L 


HOMOPHTHALIC ACIDS, bt 





with isuvitic acid.1 It crystallizes from water in short, rhom- 
bic prisms, which form saw-shaped aggregates and melt at 
175°. On heating with soda-lime it yields toluene and on 
fusion with caustic potash is resolved into carbon dioxide 
and orthotoluic acid. If it be heated with acetyl chloride, 
homophthalic anhydride, C,H,O3, is formed and_ crystallizes 
from benzene in long, pliant prisms, melting at 141°. 
Ae tea 

Homophthalimide, OHS we, 

| CO—NH 

ing ammonium phthalate; the distillate forms a crystalline 
mass covered with long crystals and crystallizes from glacial 
acetic acid in short needles, melting at 233°2 It dissolves in 
alcohol forming a solution which has a green fluorescence; on 
heating with caustic potash, methyl alcohol and methyl iodide, 
dimethylhomophthalimide, Cy5H;(CH,),NO,, 1s formed, and erys- 
tallizes from hot water in flat needles, melting at 119°—120°. 
On further heating with caustic potash and methyl iodide, ¢77- 
methylhomophthalimide C,H,(CH,),NO,, is obtained, and forms 
long needles, which melt at 102°—103° and are insoluble in 


alkalis. 


is obtained by heat- 


CH,—CO 

Homophthalmethylimide, C,H, >, 1s formed by 

\co—ncH, 

heating the methylamine salt of homophthalic acid and distils at 

314°—318°. It crystallizes from boiling water in long needles, 

melting at 123°, and is converted into trimethylhomophthalimide 
by heating with caustic potash and methyl iodide. 

When this substance is heated to 230°—240° with fuming 
hydrochloric acid, methylamine is eliminated and the anhydride 
of a dibasic acid formed, which is also formed from dimethyl- 
homophthalimide with elimination of ammonia, and crystallizes 
from alcohol in flat needles, melting at 82°5°—83°. In this 
compound and also in dimethylphthalimide, the two methyl 
groups are combined with one carbon atom, the constitution of 
the two bodies being represented by the following formule : # 


Dimethylhomophthalimide. Anhydride. 
C(CH,),.CcO C(CH,),.CO 
CHC | LG 
CO—— NH CO—O 


1 Monatsh. Chem. vi. 168. 
2 Gabriel, Ber. Deutsch. Chem. Ges. xix. 1653. 
3 [bid, ti. 2363; xx. 1198. 


276 


IBZ AROMATIC COMPOUNDS. 


Homo-orthophthalamic acid is formed when benzyleyanide- 
orthocarboxylic acid is heated with concentrated sulphuric 
acid and the solution poured into water : 


PAN PH CO.NH, 
CoH + H,O = Vena | 
CO,H CO,H 


It crystallizes in needles, which melt at 185°—187° and on 
further heating are converted into orthohomophthalimide, while 
acid ammonium homo-orthophthalate is formed when it is boiled 
with water.) 3 

Homo-orthophthalonitru, C,.H,(CN)CH,.CN. When ortho- 
tolunitril is heated almost to the boiling point and treated with 
chlorine, orthocyanobenzyl chloride, C,H,(CN)CH,Cl, is obtained. 
This substance forms crystals, melting at 60°—61°5° and is 
converted by heating with potassium cyanide and dilute alcohol 
into the nitril; which crystallizes in small, colourless flakes, 
melting at 81°. If it be heated with sulphuric acid and the 
solution poured into water, homophthalimide separates out. 
Cyanophenylacetic acid is probably first formed in this reaction 
and then undergoes an intermolecular change.’ 


/PACN /©H,00.0H 
C.H, yee) = Such cerener, 
\on ] Non 
CH,.CO.OH CH,.CO. 
CHC 7 Merwe i » 
CN \co.NH 


Homoterephthalic acid has been prepared by the oxidation of 
propylisopropylbenzene with dilute nitric acid; it is a powder, 
which is insoluble in almost all solvents and sublimes when 
heated without melting? ; 


1 Ber. Deutsch. Chem. Ges. xx. 1203. 
2 Gabriel and Otto, ibid. xx. 2222 ; Gabriel, ibid, xx. 2499. 
3 Paternd and Spica, ibid. x. 1746. 


THE PROPYLBENZENES. 153 


PHTHALIDECARBOXYLIC ACID, C,H,0,. 


The product of the action of orthoxylylene bromide on 
sodmalonic ether or sodaceto-acetic ether is hydrindonaph- 
thenecarboxylic acid, and this is oxidized in alkaline solution 
by potassium permanganate in the following way: 


CH 
CHC, >CH.COM ef0 ye 
CO.0H 
CH + 00, + 2H,0. 
C0.CO.0H 


The dibasic acid, which is thus formed, decomposes on heating 
with formation of phthalic acid and phthalic anhydride, while 
it is reduced to phthalidecarboxylic acid by the action of sodium 
amalgam on its aqueous solution : 


C.H,.CO.OH C,H,.CO.OH C.H,.CO 

| | | 

CO + 2H = CH.OH =| CHO "+ HAO, 
| | | 

CO.OH CO.OH CO.OH 


It crystallizes from hot water in lustrous flakes, melting at 
149°5°, and decomposes at 180° into carbon dioxide and 
phthalide.! 


THE PROPYLBENZENES. 


2360 Jsopropylbenzene or Cumene, C,H;.CH(CH,),, Gerhardt 
and Cahours found that the cwmznol, C,,H,,O0, which is contained 
in Roman cumin oil (Cuminum cyminum) together with cymene 
(cyméne), is the aldehyde of ewmie acid, C,)H,,0,, which decom- 
poses on heating with baryta into carbon dioxide and cumene 
(cuméne).2 The latter is oxidized to benzoic acid by dilute 
nitric acid,? and was subsequently considered to be propylben- 
zene, This was prepared synthetically by Fittig, Schiffer and 


1 Scherks, Ber. Deutsch. Chem. Ges, xviii. 378. 
2 Ann. Chem. Pharm. xxxviii, 88. 
3 Abel, ibid. Ixiii. 308. 


154 AROMATIC COMPOUNDS. 


Konig, by the replacement of an atom of hydrogen in benzene 
by primary propyl; the hydrocarbon thus obtained, however, 
proved not to be identical with cumene and these chemists 
therefore looked upon the latter as isopropylbenzene This 
view was confirmed by Jacobsen, who prepared cumene by the 
action of sodium on a mixture of bromobenzene, isopropyl iodide 
and ether.? It may also be obtained by the action of aluminium 
bromide on a mixture of benzene and isopropyl bromide or 
normal propyl bromide,*® since Kekule and Schrotter have shown 
that the latter is converted into isopropyl bromide by heating 
with aluminium bromide ;* the chlorides may be employed 
in these reactions instead of the bromides.> Liebermann obtained 
cumene by heating benzidene chloride, C,H;.CHCl,, with zinc 


methyl : ® 
CH 


C.H,.CHCl, + Zn(CH,), = C,H, CHC "st ZnCl 
CH, 


It is a liquid which boils at 155° and has a specific gravity of 
0880 at 0°. On treatment with bromine and a little aluminium, 
it decomposes with formation of hexbromobenzene, isopropyl 
bromide and their substitution products (Gustavson), 

Parabromocumene, C,H,Br.CH(CH,),, 1s formed when bromine 
is gradually added to well-cooled cumene, in which a little 
iodine has been dissolved. It is a liquid, boils at 216°—217°5°, 
and is converted into parabromobenzoic acid by oxidation with 
potassium permanganate.’ 

Orthobromocumene is formed by the action of phosphorus 
pentabromide on orthocumenol, and is a liquid, boiling at 
205°—207°,8 which is however probably a mixture of the 
isomeric bromocumenes. 

Pentabromocumene, CyH,Br,, is formed when a mixture of 
cumene and an excess of bromine is allowed to stand for a few 
weeks, It crystallizes from alcohol in stellate groups of needles, 
which have a magnificent lustre, melt at 97° and are decom- 
posed by boiling alcoholic potash with loss of bromine, it being 
thus proved that a portion of the bromine is contained in the 
alcohol radical. 


1 Ann. Chem. Pharm. exlix. 324. 2 Ber. Deutsch. Chem. Ges. viii. 1260. 
3 Gustavson, ibid. xi. 1251. 4 Ibid. xii, 2279. 
> Silva, Bull. Soc. xliii. 317. 6 Ber. Deutsch. Chem. Ges. xiii. 45. 


” Jacobsen, ibid. xii. 429. 

8 Fileti, Gaz. Chim. xvi. 113. ; Ber. Deutch. Chem. Ges. xix. Ref 553. 

* Meusel, Zeitschr. Chem. 1867, 822 ; Fittig, Schiffer and Konig, Ann. Chem. 
Pharm. exlix. 826. 


BROMCUMENE. 155 





Para-iodo-cumene, C,H,1.CH(CH,),, has been prepared from 
paramidocumene, and is a liquid, which has an aromatic 
odour, boils at 284° and yields para-iodobenzoic acid on 
oxidation. 

Cumeneparasulphonic acid, C,H,(C,H,)SO,H, was first pre- 
pared by Gerhardt and Cahours, who dissolved cumene in 
fuming sulphuric acid, and was subsequently investigated by 
Jacobsen? and Fittig, Schiffer and Konig.* It crystallizes in 
anhydrous, nacreous scales, which are very deliquescent. The 
following are its most characteristic salts: 

Barium cumeneparasulphonate, (C,H,,SO.),Ba + H,O, crystal- 
lizes from hot water in nacreous plates, which readily lose their 
water of crystallization on heating. One hundred parts of the 
solution saturated at 16° contain 4:4 parts of the anhydrous 
salt (Claus and Tonn). 

Strontium cumeneparasulphonate, (CyH,,SO,),Sr+2H,0, forms 
stellate groups of needles, which dissolve in an equal weight of 
cold water. When the saturated solution is heated to 100°, 
it solidifies to a crystalline mass, consisting of the anhydrous 
salt, which re-dissolves on cooling. 

Cumeneparasulphamide, C,H ,(C,H,)SO,.NH,, forms crystals, 
which melt at 112° (Claus and Tonn). Potassium permanganate 
oxidizes it to a sulphamic acid, which is converted into para- 
hydroxybenzoic acid on fusion with caustic potash (Spica). 

Hydroxyisopropylbenzenesulphonic acid, C,H,(SO,H)C(OH) 
(CH,),, 1s formed by the oxidation of cumeneparasulphonic acid 
with potassium permanganate. It forms a potassium salt, which 
is readily soluble in alcohol and is converted by treatment with 
phosphorus chloride and then ammonia into propenylbenzene- 
sulphamide, C,H,(SO,.NH,)C,H,, which melts at 152°. 

Cumene-orthosulphonic acid is formed, according to Spica, in 
small quantity in the preparation of the para-acid,°’ and is the 
chief product when cumene is sulphonated at 100°, or when a 
solution of cumene in fuming sulphuric acid is allowed to stand 
for several weeks.® It is extremely soluble in water and crys- 
tallizes in small, very deliquescent needles. It is converted 
into orthocumic acid when its salts are fused with sodium 


formate. 
1 Louis, Ber. Deutsch. Chem. Ges xvi. 105. 
2 Ann. Chem. Pharm. exlvi. 86. 
3 Ibid. cxlix. 329. 
4 Meyer and Baur, Ber. Deutsch. Chem. Ges, xii. 2239. 
5 Tbid, xii. 2367. ' 
6 Claus, Woge and Tonn, ibid. xviil. 1239. 


156 | AROMATIC COMPOUNDS. 


Bariwm cumene-orthosulphonate, 2(C,H,,SO,),Ba+7H,0, crys- 
tallizes in warty masses composed of needles; 100 parts of 
the solution saturated at 16° contain 16°5 parts of anhydrous 
salt. 

Cumene-orthosulphanvide crystallizes in lustrous needles, melt- 
ing at 127°. Potassium permanganate oxidizes it to a sul- 
phamic acid, which is converted into salicylic acid by fusion 
with caustic potash. 

The cumenesulphonic acids yield the cumophenols on fusion 
with caustic potash. 

Paracumophenol, C,H,(OH)CH(CH,),, crystallizes in needles, 
melts at 61° and boils at 228°—229°. 

Paracumophenyl methyl ether, C,H,(OCH,)CH(CH,),, is a 
liquid, which smells like aniseed and boils at 212°—213°. 

Paracumophenyl ethyl ether, C,H,(OC,H,;)CH(CH,),, boils at 
220° and yields ethylparahydroxybenzoic acid on oxidation. 

Orthocumophenol is a liquid, which boils at 218°5°, does not 
solidify in a freezing mixture and gives a violet colouration 
with ferric chloride. Its ethyl ether boils at 213° and yields 
an oily liquid on oxidation, which is probably ethylsalicylic acid. 

Fileti obtained a cumophenol from cumidine, which boils at 
212°—212°5° and which he considers as the ortho-compound.? 
This substance is obviously a mixture, since cumidine itself is a 
mixture of several isomerides. 

Metacumophenol was prepared by Jacobsen by heating isohy- 
droxycumic acid, C,H,(OH)CH(CH,),CO,H, to 190° with hy- 
drochloric acid. It boils at 228° and solidifies on cooling to a 
fibrous, crystalline mass, melting at 26°. Its aqueous solution is 
coloured a faint blue by ferric chloride, which produces a green 
colouration in an alcoholic solution.® 

Nitrocumene, C,H,(NO,)CH(CH,),, is formed as an oily liquid 
when cumene is dissolved in fuming nitric acid and the solution 
precipitated with water (Nicholson).* 

According to Posspechow, one part of cumene is gradually 
added to 2'5 parts of nitric acid of sp. gr. 1°52, which is well 
cooled with ice, and the product purified by distillation with 
water. It decomposes on boiling, solidifies in solid carbon 


gros 


dioxide and melts at —35°. 


1 Paternd and Spica, Gaz. Chim. ital. vi. 535; Spica, ibid. viii. 406 ; ix. 433. 
2 Ibid. xvi. 113; Ber. Deutsch. Chem. Gres, xix. 551. 

8 Ibid. xi. 1062 ; see also Widmann, ibid, xix, 251. 

4 Ann. Chem. Pharm. \xv. 58. 

5 Ber. Deutsch. Chem. Ges. xix. Ref. 169. 


——- i nai a, 


NITROCUMENE. . ey 


Trinitrocumene, C,H,(NO,),CH(CH,),, is formed by heating 
cumene with a mixture of nitric and sulphuric acids, and crys- 
tallizes from hot alcohol in long, lustrous needles, melting at 
109° (Fittig, Schiffer and Konig). 

Amidocumene or Cumidine, C,H,CN H,),CH(CH,),, was pre- 
pared by Nicholson from nitrocumene by reduction with am- 
monium sulphide. It is an oily liquid, which rapidly becomes 
yellow and finally dark-brown in the air and has a characteristic 
odour and a burning taste. It solidifies in a freezing mixture 
to quadratic tablets, which rapidly melt when the temperature 
is allowed to rise. One specimen was observed to solidify at 
the winter temperature and remained solid throughout the 
summer. It boils at 225°, colours pine-wood yellow, in the 
same way as aniline, and forms salts, which crystallize well. 

Nitrocumidine, C,H,(NO,)(NH,)CH(CH,),, was obtained by 
Cahours by the reduction of the product obtained by the action 
of a mixture of nitric and sulphuric acids on cumene, which 
he considered to be dinitrocumene ; but which is the trinitro- 
compound and, like trinitropseudocumene, loses ammonia on 
reduction. Nitrocumidine crystallizes in yellowish scales, 
melting at 100°, and forms salts, which crystallize well? 

Nitrocumene and the products obtained from it are obviously 
mixtures of isomeric compounds, the existence of which was 
unsuspected at the period of their preparation. 

Paramidocumene, C,H,(NH,)CH(CH,),, is formed when 
equal molecules of zine chloride, aniline and isopropylalcohol 
are heated to 260°. It is a liquid, which has an aromatic 
odour, becomes brown in the air and boils at 216°—218° 

2361 Propylbenzene, C,H,.C,H,, was first prepared by Fittig, 
Schiffer and Konig by the action of sodium on a mixture of 


_bromobenzene and propyl iodide,® and was subsequently obtained 


by Paterno and Spica by the gradual addition of zinc ethyl to 
benzyl chloride. It is also formed, together with other pro- 
ducts, when a mixture of benzene and aluminium chloride is 
acted on by allyl chloride in the cold,® while diphenylpropane 
and a little isopropylbenzene are formed if the mixture be 
heated. It is a liquid, which has a pleasant smell, boils 
at 157°, has a sp. gr. of 0°881 at 0° and only yields liquid 


1 Jahresh. Chem. 1847-1848, 665. 2 Louis, loc. cit. 

3 Ann. Chem. Pharm. exlix. 324. 4 Gaz. Chim. ital. vii. 21. 
5 Wispek and Zuber, Ann. Chem. Pharm. cexviii. 374. 

6 Silva, Bull. Soc. Chim. xliii. 817 and 588. 


158 AROMATIC COMPOUNDS. 


substitution products when acted on by a mixture of nitric and 
sulphuric acids. 

Parabromopropylbenzene, C,H,Br.C,H,, 1s formed when the 
hydrocarbon is treated with bromine in presence of iodine ; it 
is a liquid, which boils at 220° and is oxidized to parabromo- 
benzoic acid by nitric acid. The same compound is also 
formed, accompanied by orthobromoprepylbenzene, when bromine 
is allowed to act upon the hydrocarbon in the dark ; the liquid 
thus prepared has a persistent, pleasant odour, boils at 221°— 
223° and yields a mixture of para- and ortho-bromobenzoic 
acids on oxidation with potassium permanganate.” 

When propylbenzene is treated with bromine in the sunlight, 
a monobromide is first formed, which probably has the constitu- 
tion C,H;.CHBr.CH,.CH,. The dibromide, C,H,;.CBr,.CH,.CHg, 
is formed by the further action of bromine, while the com- 
pound, C,H,.CHBr.CHBr.CH,, which will be subsequently 
described, is formed if the action be carried on in a hot solution 
in the dark (Schramm). 

Fittig, Schiffer and Konig obtained a viscid mass, consisting 
chiefly of tetrabromopropylbenzene, C,H,Br,, by the action of 
an excess of bromine on propylbenzene. 

Para-iodopropylbenzene, C,H,1.C,H,, was prepared by Louis 
from paramidopropylbenzene as a liquid which has an aromatic 
odour, boils at 250° and is converted into para-iodobenzoic acid 
by oxidation. 

Propylbenzenesulphonie acid, C,H,(C,H,)SO,H, is formed in 
two isomeric modifications, when propylbenzene is dissolved in 
slightly fuming sulphuric acid. These compounds can be 
separated by means of their barium salts. 

Barium propylbenzeneparasulphonate, (CyH,,SO,),Ba, crystal- 
lizes in anhydrous plates. 

Barium propylbenzeneorthosulphonate, (CyH,,SO,),Ba + 2H,0, 
is more readily soluble in water and crystallizes in fascicular 
groups of microscopic needles. 

When these two salts are converted into the corresponding 
potassium salts and the latter fused with caustic potash, the 
propylphenols are obtained. 

Parapropylphenol, C,H,(C,H,)OH, has also been prepared 
from paramidopropylbenzene * and forms an oily liquid, which 


1 R. Meyer, Journ. Prakt. Chem.. [2] xxxiv. 101. 
2 Schramm, Ber. Deutsch. Chem. Ges. xviii. 1274. 
3 Spica, Gaz. Chim. Ital. viii. 406. 

4 Louis, Ber. Deutsch. Chem. Ges. xvi. 105. 





THE PHENYLPROPYL ALCOHOLS. 159 





has an aromatic odour, boils at 230°—252° and does not solidify 
in a freezing mixture. Its aqueous solution gives a faint violet 
colouration with ferric chloride, which changes to green on 
standing. 

Parapropylphenyl methyl ether, C,H,(C,H,)OCHg, is a liquid, 
which has an odour resembling that of aniseed, boils at 
214°—215'5° and is oxidized by chromic acid to anisic acid. 

Orthopropylphenol boils at 224°6°—226°6° and forms a methyl 
ether, which boils at 207°—209. 

Propylpyrogallol, C,H,(OH),C,H,. The dimethyl ether of 
this substance occurs in the fraction of creosote which boils at 
285° (Part IV. p. 37), and decomposes, when heated with concen- 
trated hydrochloric acid to 130°, into methyl chloride and 
propylpyrogallol, which crystallizes from benzene in prisms, 
melting at 79°—80°, and is extremely soluble in water and 
alcohol. 

Propylpyrogallol dimethyl ether, C,H,(OCH,;)(OH)C3H.,, is an 
oily liquid, which boils at 285° and is converted by acetic an- 
hydride into the acetyl-derivative, C,H,(OCH,)(OC,H,0)C,H., 
which crystallizes in white prisms and melts at 87°. It is con- 
verted by bromine into the compound C,Br,(OCH,)(OH)C,H., 
which forms crystals, melting at 108°—109°, and yields the 
dimethyl ether of dihydroxyquinone (Part JIT. p. 156) on 
oxidation.! 

Paramidopropylbenzene, C,H, NH,)C,H,, was obtained by 
Louis by heating aniline with propyl alcohol and zine chloride 
to 260°, as a liquid which has an aromatic odour, boils at 
224°—226° and becomes brown in the light. 


THE PHENYLPROPYL ALCOHOLS. 


2362 Primary phenylpropylalcohol, C,.H,;.C,H,.OH. The cinna- 
mic ether of this occurs, together with that of cinnyl or phenyl- 
allyl alcohol, C,H;.CH—CH.CH,.OH, in liquid styrax (p. 27)? 
The alcohols are obtained by the hydrolysis of the ethers and 
do not require to be separated, since the latter is converted into 
phenylpropyl alcohol by the action of sodium amalgam. It is 

1 Hofmann, Ber. Deutsch. Chem. Ges. viii. 66 ; xi. 329. 


* Riigheimer, Ann. Chem. Pharm. clxxii. 122; Miller, ibid. clxxxviii. 201 ; 
Hatton and Hodgkinson, Journ. Chem. Soc. 1881, i. 319. 


160 AROMATIC COMPOUNDS. 


a thick, powerfully refractive liquid, which has a faint, charac- 
teristic odour, boils at 235° and does not solidify at —18°. 

Primary phenylpropyl chloride, C,§H;.C,;H,Cl, 1s obtained by 
heating the alcohol with concentrated hydrochloric acid under 
pressure, and is a liquid, which has an odour resembing that. of 
cymene, boils at 219° and is converted by boiling alcoholic 
potash into ethyl phenylpropyl ether, CoH,;.C;H,0.C,H,, which 
boils at 220° 

Primary phenylpropyl acetate, C,H,.C,H,0.CO.CHg, 1s formed 
by the action of acetyl chloride on the alcohol as an almost 
odourless liquid, boiling at 244°—245°, 

Phenylpropylamine, C,H,;.C,H,.NH,, is obtained when 
sodium amalgam is gradually added to an alcohol solution 
of cinnamylaldehydehydrazone which contains acetic acid : 


C.H,.CH—CH.CH=N,H.C,H, + 6H = 
C.H,.CH,.CH,.CH,.NH, + H,N.C,H,. 


It is separated from the aniline, which is simultaneously 
formed, by the method which has already been described in 
connection with secondary styrolamine. It is a lquid, which 
boils at 215°—216°, rapidly absorbs carbon dioxide from the air, 
and forms a strongly alkaline solution in water, in which it 
is only slightly soluble ; it volatilizes when the aqueous solution 
is boiled and forms a vapour, which has an extremely penetrating 
odour? 

Methylbenzylearbinol or phenylisopropyl alcohol, C,H,.CH,.CH 
(OH)CH,, is formed by the action of sodium amalgam and 
water on the corresponding ketone, and is a pleasant-smelling 
liquid, which boils at 215° and is converted into the chloride 
C,H;.CH,.CHCLCH,, by heating with hydrochloric acid. This 
partially decomposes on distillation into hydrochloric acid and 
allylbenzene, which is also formed when the chloride is treated 
with alcoholic potash (Errera). The same chloride is also formed, 
together with the primary derivative, by the action of chlorine 
on boiling propylbenzene (see also p. 7). 

Phenylisopropylamine, C,.H;.CH,.CH(NH,)CH,, is obtained by 
the action of bromine and caustic potash on phenylisobuty- 
ramide, C,H;.CH,CH(CH,)CO.NH, (see Part IV. p. 113). It is 
a strongly refractive liquid, and boils at 203°.% 

1 Errera, Gaz. Chim. Ital. xvi. 310. 


* Tafel, Ber. Deutsch. Chem. Gres. xix. 1930. 
3 Edeleano, ibid. xx. 616. 


PROPIOPHENONE. 161 





Lthylphenylearbinol, C,H;.CH(OH)CH,.CH;, has also been 
prepared from the corresponding ketone,! and boils at 215°— 
217°. It is converted by hydrochloric acid into the chloride, 
C,H,.CHClLCH,.CH,, which boils at 200°—205°, but decomposes 
to a large extent into hydrochloric acid and allylbenzene. 
It is readily converted by silver acetate into the acetate, 
C,H;.CH(OC,H,0)CH,.CH,, a liquid which boils at 227° and 


has a fruity odour. 


KETONES, (,H,,0. 


2363 Lthylphenylketone or Propiophenone, C,H,.CO.C,H,, has 
been prepared by Freund by the action of zine ethyl on benzoyl 
chloride,” while Bechi obtained it by the gradual addition of 
sodium to a very dilute solution of ethyl iodide and benzoyl 
chloride. Barry then prepared it by the distillation of a 
mixture of calcium propionate and calcium benzoate, and Pampel 
and Schmidt by the action of aluminium chloride on a mixture 
of benzene and propionyl chloride. It is a liquid, which has a 
very pleasant odour, boils at 210°, does not combine with acid 
sodium sulphite and is oxidized by chromic acid solution to 
acetic acid and benzoic acid. 

Nitropropiophenone, CgH,(NO,)CO.C,H,, is formed when the 
ketone is brought into well-cooled fuming nitric acid. It crys- 
tallizes from alcohol in small, well-developed prisms, melting 
at 100°. 

A syrupy nitropropiophenone is obtained at a Ingher tem- 
perature, so that thisketone behaves in a precisely similar manner 
to acetophenone. 

Amidopropiophenone, Cg.H,(NH,)CO.C,H,;, is formed by the 
action of tin and hydrochloric acid on the alcoholic solution 
of the crystallized compound, and forms a syrup which smells of 
strawberries. Its hydrochloride is readily soluble in water and 
gives a granular crystalline platinichloride (Barry). 

Methylbenzylketone, C,H,;.CH,.CO.CH,, is obtained by the 
distillation of a mixture of barium acetate and barium phenyl- 
acetate, as well as by the action of phenylacetyl chloride on zinc 
methyl® It is a liquid, which has a pleasant odour, boils at 

1 Barry, ibid. vi. 1006 ; Errera, loc. cvs. 
2 Ann. Chem. Pharm. exviii. 20; Kalle, zbid. exix. 166. 


3 Ber. Deutsch. Chem. Ges. xii. 463. 4 Ibid. xix. 2896. 
5 Radziszewski, ibid. iii. 198. 6 Popow, ibid. v. 500. 


162 AROMATIC COMPOUNDS. 


215°, readily combines with acid sodium sulphite and is 
oxidized by chromic acid solution to acetic and benzoic 
acids. When gently warmed with sulphuric acid, the _sul- 
phonic acid, CH,.CO.CH,.C,H,.SO,H, is formed; on further 
heating however decomposition into acetic acid and benzyl- 
sulphonic acid takes place :? 


C,H,.CH,.CO.CH, + S0,(OH), = 
C,H,.CH,,.80,.0H + HO.CO.CH,, 


PHENYLPROPIONYL COMPOUNDS. 


2364. The two phenylpropionic acids which can exist according 
to theory are both known: 


a B 
CH, CH,.C,H, 
| 
CH—C,H, CH, 
CO,H CO,H 


The second of these has been obtained by the addition of 
hydrogen to cinnamic acid, C,H,.CH—CH.CO,H, the constitu- 
tion of which is accurately known, and it hence follows that the 
a-acid must possess the constitution which is ascribed to it 
above, this being further proved by the fact that it is oxidized 
in alkaline solution by potassium permanganate to atrolactic 
acid,?, CH,.C(OH)(C,H,)CO,H, only tertiary hydrogen atoms 
being converted into hydroxyl in this way.® 

a-Phenylpropionic acid was discovered by Kraut and named 
blastophenylpropionte acid (BAacTos, twig), while the isomeric 
acid was termed stichophenylpropionic acid (ati’yos, a row). 
Fittig and Wurster then investigated this acid more completely,° 
and named it hydratropic acid, since it may be obtained by 
the action of sodium amalgam and water on atropic acid, 
CH,—C(C,H,)CO,H, or the dibromohydratropic acid, 
CH,Br.CBr(C,H,)CG,H, which is formed by the combination 


1 Krekeler, Ber. Deutsch. Chem. Ges. xix. 2623. 

2 Ladenburg and Riigheimer, ibid. xiii. 373. 

3 Meyer and Baue, ibid. xii. 2238; v. Miller, cbéd. xi. 1526 and 2216; xii. 
1542; Tanatar, zbid. xii. 2293 ; xiii. 159. 

4 Ann. Chem. Pharm. exlviii. 244. 5 Ibid. cxcv. 164. 





PHENYLPROPIONYL COMPOUNDS. 163 





of bromine with the latter, atrolactic acid being also the final 
product in this case. 

Hydratropic acid is a strongly refractive oily liquid, which 
has almost the same consistency as glycerol and becomes very 
viscous at —20° without solidifying. It boils at 264°—265°, is 
volatile with steam and is heavier than water, in which it is 
only very slightly soluble. 

Caleiwm hydratropate, (C,H,O,),Ca + 2H,O, crystallizes from 
a hot solution on cooling in broad, opaque needles, which often 
unite to form large druses. If the solution be allowed to 
evaporate spontaneously however, long, lustrous, transparent, 
crystals, containing three molecules of water, are obtained. 

Silver hydratropate, C,H,O,Ag, separates from boiling water 
in scales. 

Paranitrohydratropic acid, C,H,(NO,)C,H,.CO,H, is formed 
together with the ortho-compound, from which it may be separated 
by means of its crystalline barium salt, which is scarcely soluble 
in absolute alcohol, while that of the ortho-acid forms a readily 
soluble, gummy mass. 

Paranitrohydratropic acid separates from hot water in short, 
thick crystals, melting at 87°—88", and is oxidized to paranitro- 
benzoic acid by chromic acid solution. 

Orthonitrohydratropie acid forms readily-soluble crystals, melt- 
ing at 110°, and is oxidized by potassium permanganate to 
orthonitrobenzoie acid. 

Paramidohydratropic acid, C,H,(NH,)C,H,.CO,H, crystallizes 
from water in thick, yellowish plates, which melt at 128°. It 
forms unstable metallic salts, but stable compounds with acids. 

Atroxindol, C,H,NO, is homologous with oxindol and is 
formed by the reduction of orthonitrohydratropic acid, the 
orthamido acid passing immediately into the lactone : 


NH 
ei Mee H, "00 + HO. 
\cH—CO.0H — oe 
| | 
CH, CH, 


It forms crystals, which melt at 119°, are slightly soluble in 
cold, more readily in hot water and commence to sublime at 
100°. When freshly prepared it has a fecal odour, which 
changes to that of flowers after recrystallization.1 


1 Trinius, Ann. Chem. Pharm. cexxvii. 262. 


164 AROMATIC COMPOUNDS. 


B-Phenylpropionaldehyde, C,H,.C,H,.CHO, was prepared by 
Etard in a similar manner to phenyl acetaldehyde (p. 10), 
by decomposing the compound which is formed between propyl- 
benzene and chromyl chloride with water.’ It is a liquid, which 
boils at 208° and forms a crystalline compound with acid sodium 
sulphite. 

2365 B-Phenylpropionic acid. This acid, which is known 
by many different names, was discovered by Erlenmeyer 
and Alexejew and named homotoluic acid. Their investi- 
gation was undertaken with the intention of decomposing 
cinnamic acid, which Bertagnini had obtained synthetically by 
heating benzaldehyde with acetylchloride, into benzaldehyde 
and acetaldehyde. In order to accomplish this, they acted 
upon it with sodium amalgam and water and thus found that 
cinnamic acid combines with hydrogen.? 

Popow prepared the same acid by heating cinnamic acid with 
hydriodic acid,? and Schmitt, who named it cwmoylic acid, by the 
action of sodium amalgam and water on phenyldibromopropionic 
acid, C,H,.CHBr.CHBr.CO,H, which is formed by the com- 
bination of cinnamic acid with bromine.t Swarts, who obtained 
it by the action of sodium and carbon dioxide on bromostyrolene 
(a-phenylbromethylene) (p. 33), gave it the name of hydro- 
cunnanuc acid,’ which has been universally accepted. Fittig and 
KGesow prepared its nitril by the action of potassium cyanide 
on styrolyl chloride (p. 8), and converted this without 
purification into hydrocinnamic acid. It has also been ob- 
tained by Lydia Sesemann, who termed it benzylacetic acid, 
together with dibenzylacetic acid, (C,H;.CH,),CH.CO,H, by 
heating crude sodaceto-acetic ether with benzylchloride and 
hydrolysing the product with potash.’ Riigheimer has also 
prepared it by the oxidation of phenylpropyl alcohol and 
Conrad by heating benzylmalonic acid,? C,H,.CH,.CH(CO,H),. 
It has been observed among the products of the pancreatic 
fermentation of albuminoids?? and the products of putrefaction 
of the brain of the ox (p. 12).4 


1 Ann. Chim. Phys. [5] xxii. 254. 

2 Ann. Chem. Pharm. cxxi. 875; Erlenmeyer, ibid. exxxvii. 327. 

3 Zeitschr. Chem. 1865, 111. 

4 Ann. Chem. Pharnu exxvii, 329. ° Ibid. exxxvii, 230. 
§ Ibid. clvi. 249. 

7 Ber. Deutsch. Chem. Ges. vi. 1085 ; x. 758. 

8 Ann. Chem. Pharm. c)xxii. 122. 

® Ber, Deutsch, Chem. Ges. xii. 752. 

10 H. and E. Salkowski, Ber. Deutsch. Chem. Ges. xii. 107 and 649. 
UN Stockli, Jowrn. Prakt. Chem. [2] xxiv. 17. 


HYDROCINNAMIC ACID. 165 


In order to prepare hydrocinnamic acid, 1 part of cinnamic 
acid is heated for an hour with 4 parts of hydriodic acid of 
boiling point 127° and a little amorphous phosphorus. The 
acid separates out on cooling in a solid cake, which is dis- 
solved in ammonia and precipitated by hydrochloric acid in 
the filtered solution. The hydrocinnamic acid which separates 
is then distilled; the almost pure compound, containing only 
a small quantity of an oily substance, passes over at about 
280°. 

Hydrocinnamic acid possesses a characteristic goat-like odour, 
melts at 47°5° and solidifies on cooling in long, brittle needles ; 
it boils at 280°, is readily volatile with steam, dissolves in 
168 parts of water at 20°, more readily in hot water, and 
separates in oily drops when the solution is slightly cooled. It 
is readily soluble in alcohol, from which it separates in in- 
distinct, apparently monosymmetric crystals. A mixture of 
hydrocinnamic and phenylacetic acids, which is obtained by the 
putrefaction of albuminoids, has a lower melting -pomt than 
either of its constituents. Such a mixture containing 35 per 
cent, of hydrocinnamic acid melts at 21° 

This acid yields benzoic acid on oxidation, accompanied by 
some benzaldehyde and an oily body, which smells like sage 
and does not combine with acid sodium sulphite, This was 
only obtained in small quantity and could not be further 
investigated (Erlenmeyer). 

Potassium hydrocinnamate, C,H,O0,K, forms broad, lustrous, 
soluble needles. 

Calcium hydrocinnamate, (C)H,O,),Ca + 2H,0, crystallizes in 
broad, lustrous needles, which form stellate groups, or, when the 
solution is gradually evaporated, in large, almost rectangular 
tablets. 

Barwm hydrocinnamate, (C,H,O,),Ba + 2H,0, forms broad 
needles, which are tolerably soluble in water. 

Silver hydrocinnamate, CjH,O,Ag, crystallizes from hot water 
in nacreous plates. 

Ferric chloride produces a dun-yellow-coloured precipitate 
in the solutions of the neutral salts. 

Methyl hydrocinnamate, C,H,0,(CH,), is a liquid, which boils 
at 238°—239° and has a characteristic odour. 

Hihyl hydrocinnamate, CjH,O,(C,H,), is a powerfully refractive 


1 Gabriel and Zimmermann, Ber, Deutsch. Chem, Ges, xiii. 1680. 
2-H. Salkowski, bid. xviii, 321. 


166 AROMATIC COMPOUNDS. 


liquid, which possesses an overpowering odour resembling that 
of pineapple and boils at 247° — 249°. 

Benzyl hydrocinnamate, C,H,O,(CH,.C,H;), is formed by 
heating benzyl acetate with sodium (Pt. IV. p. 97): 

ele DS CH is Wekee CH, 
4 | + Na, = 2 | + 2 | + H,. 

CO,.CH,.C,H, CO,.CH,.C,H, CO,Na 

It is a liquid, which has an aromatic odour, boils at 290° and 
is not easily decomposed by alkalis. When heated with sodium, 
it decomposes into toluene and cinnamic acid, so that these 
products are always formed in the preparation of the ether: + 


Or, Cr..@s te CHSC EG, te 
| ath 8] + CH;.C0,1,;. 
GOSGH at CO,H 

B-Phenylpropiomtril or Hydrocinnamonitril, C,H,.C,H,.CN, is 
the chief constituent of the ethereal oil of watercress (Wasturtiwmn 
officinale) ; 600 kilogs. of this plant, gathered when in flower, 
yielded 40 grams. of the oil, from which the pure nitril was 
obtained by fractional distillation. It boils at 261° and is converted 
into the acid by fusion with caustic potash.” 

2366 Halogensubstitution products of hydrocinnamic acid have 
been prepared by heating the corresponding derivatives of 
cinnamic acid with hydriodic acid and phosphorus. These 
compounds have a similar smell to that of hydrocinnamic acid, 
but in a less degree. 


CHLOROHYDROCINNAMIC AcIps, C,H,Cl.C,H,.CO,H. 


Melting-point. 
Ortho, needles or plates 96°5° 
Meta, small, snow-white plates. . . . 77°—78° 
Para, ‘crystals-7n0%, fe hed) 0 Eee 124° 


BROMOHYDROCINNAMIC AcIDS, C,H,Br.C,H,.CO,H. 


Melting-point. 
Ortho, serrate scales. «wae 6+. ee 


Meta, short, thick prisms ..... they 
Para, Hat needles» ve.) se ees 136° 
1 Conrad and Hodgkinson, Ann. Chem. Pharm. exciii. 298. 


2 Hofmann, Ber. Deutsch. Chem. Ges. vii. 520. 
3 Gabriel, 2bid. xv. 2291 ; Gabriel and Herzberg, ibid. xvi. 2036. 





IODOHYDROCINNAMIC ACIDS. 167 





The last of these has been obtained directly from hydro- 
cinnamic acid. 


IODOHYDROCINNAMIC AcIDs, C,H,I.C,H,.CO,H. 


Melting-point. 
Orition plates) jesse wee. ae cen) ae 102'-—103" 
Meta, small plates ....... 65°— 66° 
Para, white prisms ...... . . 140°—141° 


Paranitrohydrocinnamic acid, C,H,(NO,)C,H,.CO,H, is formed 
together with the ortho-acid when hydrocinnamic acid is dis- 
solved in well-cooled fuming nitric acid.2_ It is scarcely soluble 
in cold and only slightly in boiling water, from which it 
crystallizes in small, flat, very lustrous needles, while it separates 
from alcohol in very fine needles, melting at 163°-164°° 
Chromic acid solution oxidizes it to paranitrobenzoic acid. 

Metanitrohydrocinnamic acid has been prepared from meta- 
nitroparamidohydrocinnamic acid by means of the diazo-reaction. 
It crystallizes from hot water in long, lustrous yellow needles, 
which melt at 117°-118°4 

Orthonitrohydrocinnamic acid has been obtained in the pure 
state from orthonitroparamidohydrocinnamic acid. It separates 
from hot water in small, yellow crystals, melting at 113°.° 

Dimtrohydrocinnamic acid, C,H.(N O,),0,H,.CO,H (4: 2:1)is 
best prepared by dissolving 6 grams. of hydrocinnamic acid in 
60 grams. of cold fuming nitric acid and then adding 40 grams. 
of sulphuric acid. The mixture is allowed to cool and is then 
poured into cold water, the dinitro-acid separating out after 
some time. It crystallizes from hot water in long, yellowish, 
compact needles or short, thick prisms, melting at 126°5°.° 

Paramidohydrocinnamie acid, C,H,(NH,)C,H,.CO,H, is 
obtained by pouring a hot ammoniacal solution of paranitro- 
hydrocinnamic acid into an ammoniacal solution of the calculated 
quantity of ferrous sulphate : 


C,H,(NO,)C,H,.CO,H + 6FeSO, + 12NH, + 16H,O = 
C,H,(NH,)C,H,.CO,H + 3Fe,(OH), + 6(NH,),80,. 


1 Glaser and Buchanan, Zeitschr. Chem. 1869, at Gabriel and Zimmermann, 
Ber. Dewtsch. Chem. Gres. xiii. 1680. 

2 Buchanan and Glaser, Zeitschr. Chem. 1869, 193, 

3 Beilstein and Kuhlberg, Ann. Chem. Pharm. elxiii. 132. 

4 Gabriel and Steudemann, Ber. Deutsch. Chem. Ges. xv. 842. 

5 Gabriel and Zimmermann, 7zbid. xiii. 1680. 

6 Gabriel and Zimmermann, Joc. cif. and Ber. Deutsch. Chem. Ges. xii. 600. 


277 


168 AROMATIC COMPOUNDS. 


The mixture is boiled for five minutes, filtered and evaporated 
to a small volume, the acid being deposited in crystalline crusts, 
which melt at 131° It forms unstable metallic salts, while its 
compounds with acids crystallize well (Buchanan and. Glaser ; 
Gabriel and Steudemann). 

Paramido-orthonitrohydrocinnamic acid, C,H,(NH,)(NO,)C, 
H,.CO,H, was prepared by Gabriel and Zimmermann from dinitro- 
hydrocinnamic acid by reduction with hot ammonium sulphide. 
It crystallizes from water in flat needles or broad tablets, 
which resemble potassium dichromate in colour and melt at 
137°—139°. The hydrochloride forms colourless crystals. 

Paramidometamtrohydrocimnamec acid is obtained by heating 
paramidohydrocinnamic acid with acetic anhydride, nitrating the 
acetyl derivative, which is thus formed, and decomposing the 
product with hydrochloric acid. It forms short, thick, orange-red 
crystals, melting at 145° (Gabriel and Steudemann). 

Metamidohydrocinnamic acid, C,H,(NH,)C,H,.CO,H, is formed 
by the reduction of the corresponding nitro-acid and separates 
from hot water in octohedral or acute rhombic crystals, melting at 
84°—85°. Its hydrochloride crystallizes in scales or broad needles. 

2367 Hydrocarbostyril, CjH,NO, is the lactame of orthoamido- 
hydrocinnamic acid and is the homologue of oxindol ; it is formed 
by the reduction of orthonitrohydrocinnamic acid, the amido- 
acid losing the elements of water immediately on formation : 


CH,.CH,.CO.OH CH,—CH, 
CH ; a EER 
6 *\NH 

2 


It is best prepared from the ethyl ether of orthonitro-cinnamic 
acid, O,H,(NO,)C,H,.CO,H, by saturating its alcoholic solution 
with hydrochloric acid and adding zinc dust, the mixture being 
kept well-cooled, until an energetic evolution of hydrogen takes 
place. The addition of water then precipitates the pure 
hydrocarbostyril.? 

Buchanan and Glaser obtained it by the reduction of 
crude nitrohydrocinnamic acid with tin and hydrochloric acid,? 
while Gabriel and Zimmermann prepared it from the pure 
ortho-acid. It crystallizes from alcohol in prisms, which melt at 
163° and are readily soluble in hydrochloric acid. It is con- 
verted by phosphorus chloride into dichloroquinoline (Baeyer), 


+ H,0O. 


- 


H 
See N SEES) 


} Friedlander and Weinberg, Ber. Deutsch. Chem. Ges. xv. 1423. 
2 Loc. cit. ; Baeyer, Ber. Deutsch. Chem. Ges. xii. 46. 


HYDROCARBOSTYRIL. 169 





which can readily be reduced to quinoline, C,H,N, a base which 
is obtained by heating many alkaloids with caustic potash. 
The constitution of these compounds is shown by the following 
formulze : 


Hydrocarbostyril. Quinoline. 
CH CH, CH CH 
HC? \o% Snr! Ho? \,~ \cx 

i | | 
HC, , O I 
"A Aavaal PERE AE 
CH NH i yey 


a-Lthylhydrocarbostyril, CysH,(NC,H,)O, is formed when 
hydrocarbostyril is heated with ethyl iodide and alcoholic potash, 
or when an alkaline solution of ethylorthonitrocinnamic acid is 
heated with sodium amalgam. It is a thick, oily liquid, which 
has a faint but pleasant smell of flowers, dissolves in strong 
hydrochloric acid and is reprecipitated by water.! 

B-Lthylhydrocarbostyril, CyH,N(OC,H,), is formed by the 
reduction of ethylcarbostyril and is a mobile liquid, which has a 
penetrating but sweet smell and is decomposed by hydrochloric 
acid into alcohol and hydrocarbostyril.? 

The isomerism of these compounds is explained by the 
following formule : 


a B 
(CHCl, OH CH, 
GUC ie will | CH, | 
| | 
C,H, OC,H, 


Paramidohydrocarbostyril, CyH,(NH,)NO, is formed by the 
reduction of dinitrohydrocinnamic acid, and crystallizes from hot 
water in long needles or short, thick prisms, which melt at 211°. 
Its hydrochloride crystallizes in fine, white needles (Gabriel and 
Zimmermann). 

Hydrazinhydrocinnanic anhydride, CH,,N,O, This lactame, 
which Fischer and Kuzel have named amidohydrocarbostyril, is 
formed when an alkaline solution of hydrazinesulphocinnamic 
acid is treated with sodium amalgam and then heated with 
hydrochloric acid. The lactame is precipitated by the addition of 


1 Friedlander and Weinberg, Ber. Deutsch. Chem. Ges. xv. 2103. 
2 Ibid, xv. 1424, 


170 AROMATIC COMPOUNDS. 


hydrochloric acid and crystallizes from hot water in small plates, 
which melt at 143°. Its hydrochloride crystallizes in prisms. 
When an acid solution of the base is treated with sodium nitrite, 
hydrocarbostyril separates out. On heating the lactame with 
ethyl iodide and alcohol, ethylamidohydrocarbostyril, C;HyO,N— 
NH(C,H,), is obtained in colourless crystals, melting at 74°; it 
is a base which forms readily soluble salts. 

The isomerism of the lactame with paramidohydrocarbostyril 
is rendered evident by the following formule : 





CHS ea ae CH,—CH 

Wien 200 ChH CNT © ene a 
| \NH—CO 
NH, 


Lthylhydrocarbazostyril, CyH,0,N,(C,H,). The product of the 
action of sodium amalgam on an alcoholic solution of ethyl- 
amidocinnamic acid is ethylamidohydrocinnamic acid, which is 
converted into the nitroso-compound by sodium nitrite in acid 
solution, This is reduced by zinc dust and acetic acid to 
ethylamidohydrocinnamic acid, which decomposes on evaporation 
into water and the lactame : 


CH,—CH,—C0.0H CH,—CH 

CHL aA: _ Oe ee \coean 
NH, = SN See HI ce 

C,H, C,H,” 


Ethylhydrocarbazostyril crystallizes from hot water in long 
needles, which melt at 165°5° and can be volatilized without 
decomposition. It dissolves in cold hydrochloric acid and is re- 
precipitated by water ; when it is heated with the acid, however, 
it 1s reconverted into the hydrazine acid.” 


HYDROXYPHENYLPROPIONIC ACIDS, 
C,H,(OH)C,H,.CO,H. 


2368 Phloretic acid was first prepared by boiling phloretin 
with caustic potash? Its constitution was determined by 
Trinius, who obtained it from paramidohydratropic acid by means 

1 Ann. Chem. Pharm. cexxi. 282. 2 Fischer and Kuzel, ibid, ccxxi. 293. 


3 Hlasiwetz, Journ. Prakt. Chem. lxvii. 109 ; Ixxii. 395 ; Schiff, Ann. Chem. 
Pharm, clxxii. 356. 


HYDROXYPHENYLPROPIONIC ACID. 171 


of the diazo-reaction, and named it parahydroxyhydratropic 
acid, C,H,(OH)CH(CH,)CO,H. It crystallizes from ether in 
monosymmetric prisms or groups resembling wavellite, is 
tolerably soluble in cold, readily in hot water, has an acid, 
astringent taste and melts at 129°. On heating with baryta it 
decomposes into carbon dioxide and phlorol or 8-ethylphenol 
(p. 4), while it is resolved into acetic acid and parahydroxy- 
benzoic acid by fusion with caustic potash.? 

Phloretin, C,,H,,0;, is formed when phloridzin is boiled with 
dilute sulphuric acid,* and crystallizes in small plates, melting at 
180°. It dissolves in every proportion in alcohol, and is readily 
soluble in alkalis, but almost insoluble in cold water and 
only very slightly soluble in boiling water. On boiling with 
alkalis, it decomposes into phloretic acid and phloroglucinol, 
while on heating with acetyl chloride it forms a diacetyl 
compound, * 

It has therefore, according to Schiff, the following con- 
stitution : 


mi GH 
an aah 


Phloridzin, C,,H,,0,)+2H,O, was discovered by Koningk in the 
root bark (fXovds, bark ; p/fa, root) of the apple, pear, plum and 
cherry tree.’ It is best obtained, according to Stas,° from that 
of the apple tree by extraction with warm, dilute alcohol. It 
crystallizes in silky needles, which have a sweet taste, followed 
by a bitter after-taste, melt at 108° with loss of water, solidify at 
a higher temperature and finally fuse at 170°—171°, with 
formation of phloretin and glucosan (Schiff). It dissolves in 
1000 parts of cold water and in every proportion in boiling 
water. On boiling with dilute acids it decomposes into phloretin 
and a glucose, which Hesse has named phlorose,’ C,H,,0,, but 
which has been shown by Rennie to be identical with dextrose.§ 
Jt also combines with bases and yields a pentacetyl derivative 


1 Ann. Chem. Pharm. cexxvii. 268. 

2 Barth, zbid. clii. 96; Barth and Schreder, Ber. Deutsch. Chem. Ges. xii. 1259. 
3 Stas, ‘Ann. Chem. Pharm Ex. 200 = Schiff, ibid. ; loc. cit, 

4 Schiff, Ann. Chem. Pharm. clvi. 1. 

5 Ibid. xv. 75 and 258. 6 Toid. xxx. 192. 

7 Ibid, clxxvi. 114 ; excii. 173. 8 Journ. Chem. Soc. 1887, i. 634, 


172 AROMATIC COMPOUNDS. 





on heating with acetic anhydride, and has therefore the following 
constitution (Schiff) : 
C,H,O(OH 
9 ooHOOH), 


ey 
oo vote OH 


°"\o, H, heat 
aH HL. 


According to Rochleder, the leaves of the apple tree contain 
isophloridzin, but Schiff found that this is identical with 
phloridzin.” 

Glycyphillin, C,,H,,0,, occurs in the leaves of Smilax 
glycyphilla, which is employed in Australia, where the plants are 
abundant, as an anti-scorbutic, &c. It separates from aqueous 
ether in crystals, containing three molecules of water, and from 
solution in water in thin, brittle, four-sided prisms, containing 
four and a half molecules of water, has a sweet taste resembling 
that of licorice and decomposes on heating with dilute acids into 
phloretin and isodulcite,? so that it must possess the following 
constitution :— 


on.ZoNon,0, 
xO 


PNae 
or i. 


2369 Hydroparacumaric acid or Parahydroxyhydrocinnamic 
acid, O,H,(OH)C,H,CO,H, was obtained by Hlasiwetz by 
treating paracumaric acid, C,H,(OH)CH=CH.CO,H, with 
sodium amalgam,‘ and was prepared by Buchanan and Glaser by 
the action of nitrous acid on paramidohydrocinnamie acid.? It 
is, however, best prepared from parahydroxyphenyl-a-amido- 
propionic acid or tyrosine, C,H,(OH)CH,.CH(NH,)CO,H, 6 grms. 
of which are ground up in 5 litres of water and allowed to stand 
for two days at the temperature of an incubator in contact with 
a few flakes of putrefied pancreas. The liquid 1s then evaporated 
to a tenth of its bulk, acidified with sulphuric acid and extracted 
with ether. The residue obtained by the evaporation of the 


1 Zeitschr Chem. 1868, 711. 2 Ann. Chem. Pharm. ccxxix. 371. 
° Wright and Rennie, Jowrn. Chem. Soc. 1881, i. 237; Rennie, zbid. 1886, i. 
8 


4 Ann. Chem. Pharm. exlii. 358. 5 Zettschr. Chem. 1869, 197. 


MELILOTIC ACID. 173 





ether is extracted with water and treated with lead acetate 
solution to remove fatty acids, the filtrate being then freed from 
lead by means of sulphuretted hydrogen and evaporated to a 
syrup, from which the hydroparacumaric acid crystallizes. 
Twelve parts of this were obtained from 20 parts of tyrosine.” 
It has also been detected in human urine, in the pus from a case 
of peritonitis * and among the products of the putrefaction of flesh.‘ 

It crystallizes in monosymmetric prisms, which melt at 
128°—129°.° On further putrefaction with pancreas, it decom- 
poses into parahydroxyphenylacetic acid, paracresol and phenol, 
and is resolved into parahydroxybenzoic acid and acetic acid by 
fusion with caustic potash.® 

Its substitution products have been investigated by Stohr, who 
also found that it behaves towards Millon’s reagent in precisely 
the same way as tyrosine. 

Lithy! hydroparacumarate, C,A,(OH)C,H,.CO,.C,H,, is an oily 
liquid, which smells like rhubarb root, in which it is perhaps 
present (Stohr). 

Methylhydroparacumarie acid, C,H,(OCH,)C,H,.CO,H, . is 
obtained by the action of water and sodium amalgam on methyl- 
paracumaric acid. It forms feathery crystals or long, white 
needles, melting at 102°.7 

Melilotic acid or Hydrocwmaric acid was discovered by Zwenger 
and Bodenbender in the common melilot (Jelilotus officinalis),® 
and is formed by the action of water and sodium amalgam on 
cumaric acid or orthohydroxycinnamic acid ® and cumarin.’? It 
crystallizes from water in long needles, and from benzene in thin, 
transparent prisms, which melt at 83° and decompose on distil- 
lation into water and the anhydride. This is also formed when 
the acid is brought into contact with hydrobromic acid," and has 
the following constitution : 

O25 a OAs 
eres 
O—CO. 


Baumann, Ber, Deutsch. Chem. Ges. xii. 1451. + Ibid. xii. 279. 
Baumann, Hoppe-Seyler’s Zeitschr. iv. 307. 
EK. and H. Salkowski, Ber. Deutsch. Chem. Ges. xiii. 190. 
Stohr, Ann. Chem. Pharm. ecxxv. 57. 
Barth and Schreder, Ber. Deutsch. Chem. Ges. xii. 1259. 
Perkin, Journ. Chem. Soc. 1877, i. 411; Eigel, Ber. Deutsch. Chem. Ges. xx. 
2527. 
8 Ann. Chem. Pharm. exxvi. 262. 
® Herzfeld and Tiemann, Ber. Deutsch. Chem. Ges. x. 286. 
10 Zwenger, Ann. Chem. Pharm. Suppl. v. 122. 
11 Hochstetter, ibid. cexxvi. 355. 


ant k WO 


“I 


174 AROMATIC COMPOUNDS. 


It crystallizes in tablets, melts at 25°, boils at’ 272° and smells 
like cumarin, into which it is converted by heating with bromine 
(Hochstetter). 

The meditolol, C,H,O,. which Phipson obtained by distilling 
blossoming melilot, with water, is probably identical with this 
substance. It forms an oily liquid, smelling like the plant, and 
yields melilotic acid on boiling with caustic potash." 

Methylmelilotic acid, C§H,(OCH,;)C,H,CO,H, was obtained by 
Perkin by the action of sodium amalgam on aqueous solutions of 
a- and §-sodium methyl cumarate. It separates from hot alcohol 
in transparent crystals, which resemble those of Glauber’s salt, 
and melt at 92°. 


DIHYDROXYPHENYLPROPIONIC ACIDS, 
C.H,(OH),C,H,.CO,H. 


2370 Hydrocafferc acid (4:3:1) is formed by the action of 
sodium amalgam and water on caffeic acid, C,H,(OH),CH— 
‘CH.CO,H. It forms rhombic crystals, which are readily soluble 
in water. Its constitution corresponds to that of protocatechuic 
acid; like this, it gives a deep green colouration with ferric 
chloride, which is converted into dark red by the addition of 
sodium carbonate. It is precipitated by lead acetate and readily 
reduces Fehling’s solution and ammoniacal silver solution.? 

The following ethers have been prepared from the correspond- 
ing derivatives of caffeic acid :* 


Melting-point 
Hydroferulic acid, C,H,(OH)(OCH,)C,H,0,, 


microscopic tablets .. . 7. |. 89 =e 
Isohydroferulic acid, C,H3(OCH, \(OH)C, H 0, 

fine needles .. . . 1465 
Dimethylhydrocaffeic dh C OgH(OCH,) c, H Om 

fine needles .... . 96°—97° 
Methylenehydrocaffeic acid,®> CH < ye HeGeHOS 

Jong needles: 4 Jer. r2) tyes Bek ie eee ee 84° 


1 Compt. Rend. \xxxvi. 830. 

2 Journ. Chem, Soc. 1881, i. 415. 

3 Hlasiwetz, Ann. Chem. Pharm. exlii, 358. 

4 Nagai and Tiemann, Ber Deutsch. Chem. Ges. xi. 650. 
5 Lorenz, tbid. xiii. 756 ; Regel, ibid. xx. 421. 


ATROLACTIC ACID. 175 





Hydro-umbellie acid (6 : 2:1) is formed by the action of sodium 
amalgam and water on umbelliferon, which is the anhydride of 
umbelliferonic acid, isomeride of caffeic acid. It forms granular 
crystals, which are only slightly soluble in water and commence to 
lose water and decompose at 110°. It is not precipitated by lead 
acetate, but reduces silver solution and Fehling’s solution and 
gives a green colouration with ferric chloride. It is converted 
into resorcinol by fusion with caustic potash." 


PHENYLHYDROXYPROPIONIC ACIDS. 


2371 Airolactic acid or a-LPhenyl-a-propionic acid, 
C,H,.C(CH,)(OH)CO,H, was obtained by Wurster and Fittig 
by boiling a-bromohydratropic acid with sodium carbonate 
solution.” It is also formed by the oxidation of hydratropic 
acid with potassium permanganate,’ and when hydrochloric 
acid is added to well-cooled acetophenone containing some 
moistened potassium cyanide, the nitril being first formed 
as an oily liquid, which dissolves in the excess of hydrochloric 
acid with formation of the acid and separation of ammonium 
chloride.‘ 

Atrolactic acid crystallizes in broad needles or rhombic 
tablets, containing half a molecule of water, which is lost over 
sulphuric acid. The anhydrous acid melts at 93°—94°; it is 
readily soluble in water and is not decomposed by boiling with 
baryta water, but is resolved into atropic acid and water by 
boiling hydrochloric acid. 

Its salts have been investigated by Fittig and Wurster. 

Hihylatrolactie acid, C,H;.C(OC,H,)(CH,)CO,H. The nitril, 
C,H;.C(OC,H,)(CH,)CN, is formed when methylphenylmethy- 
lene dichloride, C,H,.CCl1,.CH;, which is obtained by the action 
of phosphorus chloride or acetophenone, is brought into a solution 
of potassium cyanide in dilute alcohol, and is converted ito the 
acid by boiling with baryta water.® The acid may also be obtained 
by passing hydrochloric acid into an alcoholic solution of bromo- 


1 Hlasiwetz and Grabowski, Ann. Chem. Pharm. cxxxix. 102. 

2 Ibid. excv. 145. 

3 Ladenburg and Riigheimer, Ber. Deutsch. Chem. Ces, xili. 374. 
4 Spiegel, 2bid. xiv. 235 and 1352. 

5 Ladenburg and Riigheimer, ibid. xiii. 2041. 


176 AROMATIC COMPOUNDS. 


hydropiiic acid, treating the ether, C,H;.CBr(CH,)CO,.C,H,, with 
sodium ethylate and decomposing the product by boiling with 
baryta water.! 

Ethylatrolactic acid is tolerably soluble in hot water and 
crystallizes from petroleum-spirit in small prisms, which melt at 
59°5°—62°, and are converted into atropic acid by boiling with 
hydrochloric acid. 

a-Chlorhydratropic acid or a-Phenyl-a-chloropropionie acid, 
C,H,.C(CH;)ClLCO,H, is formed when atrolactic acid is dis- 
solved in concentrated hydrochloric acid, and separates out after 
some hours. It may be obtained from petroleum-ether in 
crystals, which melt at 73°—74° and decompose at 110° with 
evolution of gas. It does not yield styrolene when boiled with 
sodium carbonate solution.” 

a-Phenyl-a-bromopropiome acid or a-Lromohydratropic acid, 
C,H,.CBr(CH,)CO,H, is obtained by the combination of atropic 
acid, C,H,.C(CO,H) = CH,, with hydrobromic acid,? 6-bromo- 
hydratropic acid being simultaneously formed (Merling). It may 
be prepared pure by the action of fuming hydrobromic acid on 
atrolactic acid; it is readily soluble in carbon disulphide, less 
readily in petroleum-ether, and crystallizes from a mixture of 
these in tablets, melting at 93°—94°. 

a-Phenyl-a-amidopropione acid or a-Amidohydratropre acid, 
C,H,.C(NH,)(CH,)CO,H. When the nitril of ethylatrolactic 
acid is heated to 60°—80° with alcoholic ammonia, phenyl- 
amidopropionitril is formed as an oily liquid. If it be treated 
with cold fuming hydrochloric acid and then heated with dilute 
hydrochloric acid and alcohol, the hydrochloride of the amido- 
acid, which crystallizes in concentrically grouped needles, is 
formed. If ammonia be added to the alcoholic solution of this 
salt, the free acid is obtained. It is insoluble in alcohol and 
crystallizes from a concentrated aqueous solution in feathery 
needles, which have a satin lustre and sublime at about 
260° without melting. When the aqueous solution of the 
hydrochloride is heated with sodium nitrite, pure atrolactic 
acid is formed and can thus be prepared in considerable 
quantity. 

Dibromatrolactic acid, C,H;.C(OH)CUBr,.CO,H, is gradually 


1 Riigheimer, Ber. Deutsch. Chem. Ges. xiv. 446. 

2 Merling, Ann. Chem. Pharm. ccix. i. 

3 Fittig and Kast, loc. cit. 

4 Tiemann and Kohler, Ber. Deutsch. Chem. Ges. xiv. 1980. 


TROPIC ACID. 177 


——- 





precipitated when dibromopyroracemic acid is brought into 
twenty parts of sulphuric acid and benzene added: 


CHBr CHBr 
et COn, 


CH, + CO 
ied \co,H Noo. H 


It is only slightly soluble in water and crystallizes from chloro- 
form in lustrous needles and from benzene in long, four-sided 
prisms, which melt at 167°. It is converted into atrolactic acid 
by the action of water and sodium amalgam, while it yields carbon 
dioxide, hydrobromic acid and benzoylmethyl bromide on boil- 
ing with water : 


/LBr, 
C,H,(COH)< = OO, + HBr + C,H;.CO.CH,Br 
; \CO.H 


°- 
“a 


2372 Tropic acid or a-Phenyl-8-hydroxypropionice acid, 
C,H;.CH(CH,.0H)CO,H. The isomeric alkaloids atropine and 
hyoscyamine, C,,H,,NO., which are contained in deadly night- 
shade (Atropa belladonna), the thorn-apple (Datura stram- 
monium), the henbane (fHyoscyamus niger), and others of 
the Solanaceae, decompose on boiling with baryta water into 
tropin and tropic acid,? which is also formed when #-chloro- 
hydropiic acid is heated to 120°—130° with sodium carbonate 
solution,? or boiled with potassium carbonate solution.* It 
crystallizes from hot water in needles and on the spontaneous 
evaporation of its aqueous solution in tablets, which melt at 
117°—118°. It is not affected by water at 130°, but is con- 
verted by continued boiling with baryta water into atropic 
acid, C,H,.C(CO, 2H) = CH,, 

ae eee -B-chloropropionie acid or B-Chlorohydropdic acid, 
C,H,;.CH(CH,CI)CO,H, was obtained by Ladenburg, who 
treated tropic acid with phosphorus chloride and decomposed 
the product with water, and has been prepared by Spiegel by 
heating atrolactonitril to 130° with fuming hydrochloric acid, 
the atrolactic acid which is first formed decomposing into 
water and atropic acid, the latter of which then combines with 
hydrochloric acid. The chlorinated acid is therefore also readily 

1 Bottinger, Ber. Deutsch. Chem. Gres. xiv. 1235. 

2 Lossen, Ann. Chem. Pharm. cxxxviii. 233; Kraut, zbid. exlviii. 238 ; 


Ladenburg, Ber. Deutsch. Chem. Ges. xiii. 254. 


3 Spiegel, cbid. xiv. 235 and 1352. 4 Merling, Ann. Chem. Pharm. ccix. 1, 
5 Ber, Deutsch. Chem. Ges, xii. 947. 


178 AROMATIC COMPOUNDS. 


obtained when atropic acid is heated to 100° with hydrochloric 
acid saturated at 0° (Merling). It is insoluble in cold, readily 
in hot water and crystallizes from carbon disulphide in small 
tablets, which melt at 87°—88° and volatilize at a higher 
temperature with decomposition, forming a vapour which attacks 
the eyes violently. 

a-Phenyl-B-bromopropionic acid, C,H;.CH(CH,Br)CO,H, is 
formed by heating atropic acid with hydrobromic acid and 
erystallizes from carbon disulphide in small prisms, melting at 
93°—94° (Merling). 

a-Phenyl-B-amidopropionie acid, C,H,.CH.(CH,.N H,)CO,H, is 
formed by the action of cold ammonia on the brominated acid, 
and crystallizes from hot water in lustrous plates or fine needles, 
melting at 169°5°. 

a-Phenyl-lactic acid or B-Phenyl-a-propionie acid, C,H,.CH,. 
CH(OH)CO,H, was obtained by Erlenmeyer by the action of 
hydrocyanic and hydrochloric acids on phenylacetaldehyde,! while 
Conrad prepared it by heating benzylhydroxylmalonic acid, 
C,H,.CH,.C)OH)(CO,H),, to 160°—180°2 It crystallizes from 
water in large, thick, lustrous prisms, which melt at 98° and 
decompose on further heating into formic acid and phenyl- 
acetaldehyde. 

a-Phenyl-lactonitril, C,H;.CH,.CH(OH)ON, is formed when 
freshly prepared phenylacetaldehyde is treated with anhydrous 
hydrocyanic acid and crystallizes in stellate or warty groups of 
small needles, which melt at 57°—58° and decompose at 100° 
with evolution of hydrocyanic acid. 

B-Phenyl-a-amidopropionie acid or Phenylalanine, C,H,.CH,. 
CH(NH,)CO,H. The nitril of this acid is formed by the 
action of alcoholic ammonia on the preceding compound and is 
converted into the free acid by heating with concentrated hydro- 
chloric acid.? It is also found, accompanied by other amido- 
acids, in the young shoots of Lupinus luteus.* It crystallizes 
from hot water in short, distorted prisms, and from dilute alcohol 
in small plates with a satin lustre, which are decomposed on 
heating with formation of styrolylamine (p. 7). Its compounds 
with acids and bases crystallize well. 

Paranitrophenylalanine, 2C,H,(NO,)CH,.CH(NH),)CO,H + 
3H,O, is formed when concentrated nitric acid is added to a 


1 Ber. Deutsch. Chem. Ges. xiii. 308. 

2 Ann. Chem. Pharm. ceix. 247. 

3 Erlenmeyer and Lipp, ibid. ccxix. 186. 

* Schulze and Barbieri, Ber. Deutsch. Chem. Ges. xiv. 1785. 





TYROSINE. | 179 


solution of phenylalanine in sulphuric acid, and crystallizes from 
water in stellate groups of prisms, which effloresce in the air. 
It is oxidized to paranitrobenzoic acid by chromic acid solution. 

Paramidophenylalanine, C,H,(N H,)CH,CH(NH,)CO,H+H,9, 
is obtained by the reduction of the nitro-compound with tin 
and hydrochloric acid, and is also formed when the ethyl 
ether of dinitrocinnamic acid, C,H,(NO,)CH—C(NO,)CO,H, is 
treated first with tin and hydrochloric acid and then with 
sodium amalgam and water. It crystallizes from hot water in 
lustrous, brittle prisms, which have a sweet taste. Its hydro- 
chloride, C,H,,N,O,(HCl),, forms small lustrous prisms (Erlen- 
meyer and Lipp). 

2373 Tyrosine, C,H,(OH)CH,.CH(NH,)CO,H, was discovered 
by Liebig, who obtained it by fusing freshly prepared cheese 
(rUpos) with caustic potash? It may be obtained in a similar 
manner, together with leucine, from other albuminoids, horn, 
feathers, hair, etc., and also by boiling them with dilute sul- 
phuric or hydrochloric acid, and is also formed by the putrefaction 
of such substances. It occurs both in the animal and vegetable 
kingdoms and is found in cochineal,‘ crayfish, spiders, caterpillars 
and moths, but not in butterflies, which only contain leucine.’ 
The latter also accompanies it in the liver during certain diseases.° 
Schulze and Barbieri detected it along with glutamic and aspartic 
acids in the young shoots of the gourd 7 and Lippmann obtained 
the same compounds and leucine from beet molasses.$ 

The composition of tyrosine was determined by Warren de la 
Rue and Hinterberger, while its physical and chemical proper- 
ties were first studied by Strecker ® and then more thoroughly 
by Stiideler. 

The former of these made the suggestion “that tyrosine, 
like glycocoll and leucine, is a copula occurring in many animal 
substances.” 

According to Stiideler it has undoubtedly a similar constitu- 
tion to these compounds, since it combines both with acids and 
bases, but differs from them in being a weak dibasic acid, while 


1 Freidlinder and Mihly, Ann. Chem. Pharm. ccxxix. 226. 

2 Ibid. lvii. 127 ; 1xii. 269. 

3 Bopp, zbid. lxix. 20; Hinterberger, ibid. Ixxi. 74; Leyer and Koller, ibid. 
Ixxxiii. 382; Stideler, cbid. xci. 12; Miiller, Jowrn. Prakt. Chem. lv. 162 and 
447, 

4 Warren de la Rue, Ann. Chem. Pharm. lxiv. 36. 

5 Fterichs and Stiideler, 2bid. exvi. 57. 6 Jahresb. Chem. 1856, 702. 

7 Ber. Deutsch. Chem. Ces. xi. 710. 8 Ibid. xvii. 2835. 

9 Ann. Chem. Pharm. \xxiii, 70. 


180 AROMATIC COMPOUNDS. 


these are both monobasic, Schmitt and Nasse considered it to be 
ethylamidosalicylic acid and endeavoured, but without success, 
to prepare it synthetically. ‘They found however, as a proof of 
the accuracy of their view, that it decomposes on heating into 
carbon dioxide and hydroxyethylaniline? (Pt. III. p. 206). Barth 
then showed that tyrosine is resolved into ammonia, acetic acid, 
and parahydroxybenzoic acid by fusion with caustic potash, and 
therefore looked upon it as ethylamido-parahydroxybenzoic 
acid.2 Hiifner however proved that on heating with hydriodic 
acid, ammonia and no ethylamine is formed, and Barth concluded 
from this that it is a parahydroxyphenylamidopropionic acid, 
without being able to decide whether it is derived from 
phloretic or hydroparacumaric acid. Beilstein and Kuhlberg 
considered it as a derivative of the latter and gave it the formula 
C,H,(OH)C,H.(NH,)CO,H, the position of the amido-group 
being undecided,* but were, like Barth, unable to prepare it 
synthetically. Ladenburg, who started with the view that 
tyrosine is ethyloxyparamidobenzoic acid, C,H,NH(OC,H,)CO,H, 
prepared the latter, but found it to be different from tyrosine. 
Erlenmeyer and Lipp however succeeded in preparing it by 
adding a solution of the calculated quantity of sodium nitrite 
to a well-cooled solution of paramidophenylalanine in dilute 
sulphuric acid, and in this way proved it to be parahydroxy- 
phenylalanine or parahydroxyphenyl-a-amidopropionic acid.° 

In order to prepare tyrosine, according to the method given 
by Hinterberger and Stadeler, 6 kilogr. of horn shavings, which 
give the best yield, are boiled for 16 hours with 12 kilos. of 
sulphuric acid and 60 litres of water, the volume of the liquid 
being kept constant by the repeated addition of small quantities 
of water. The liquid is then neutralized with milk of lime, 
filtered and the residue extracted twice with water. The 
solution is then evaporated to half its bulk, acidified with 
sulphuric acid, filtered and made into a thin paste with lead 
carbonate. The filtrate is treated with sulphuretted hydrogen 
and concentrated. The tyrosine, which crystallizes out, is 
separated from the thick mother liquor, which deposits crystals 
of leucine, accompanied by a little tyrosine, after standing for 
some months. These may easily be separated since tyrosine is 


1 Ann. Chem. Pharm, exxxiii. 212. 2 Ibid. exxxvi. 111. 
3 Ibid. clii. 100. 4 Tbid. clxiii. 142. 
5 Ber. Deutsch. Chem. Ges. vi. 129. 

6 Ann. Chem. Pharm. ccxix. 161. 


ee 


TYROSINE. 181 





insoluble in alcohol. One hundred parts of horn shavings yield 
3°6 parts of tyrosine and 10 parts of leucine. 

Tyrosine crystallizes in lustrous, stellate or fascicular groups 
of needles (Fig. 1), which dissolve in 150 parts of boiling water 
and in 2400 parts of cold water (Erlenmeyer and Lipp). It is 
scarcely soluble in cold alcohol and is insoluble in ether. The 
decompositions which it undergoes by heating and fusing with 
caustic potash have already been stated, as well as the fact that 
it is converted into hydroparacumaric acid by the pancreatic 


putrefaction; this acid is also formed by the putrefaction of 





Fig 1; 


albuminoids, but must be looked upon as derived from tyrosine, 
which is the first product. A transient red colouration is 
produced when tyrosine is dissolved in a few drops of sulphuric 
acid at a gentle heat. If the solution be diluted with water, 
neutralized with barium carbonate, boiled, filtered and ferric 
chloride gradually added to the filtrate, a beautiful violet 
colouration, due to the tyrosinesulphonic acid present, is 
produced.” 

If a neutral solution of mercuric nitrate (Millon’s reagent) be 
added to an aqueous solution of tyrosine as long as a yellowish 


1 Baeyer, Zeitschr. Chem. 1867, 436. 
2 Piria, Ann. Chem. Pharm. |xxxii. 251; Stiideler, cbid. exvi. 66. 


182 AROMATIC COMPOUNDS. 


white precipitate is formed, which becomes dark coloured and 
much denser after being repeatedly boiled with a few drops of 
dilute nitric acid (a few drops of fuming acid in a test tube full 
of water). 

Tyrosine has a perfectly neutral reaction, but combines with 
acids ; the hydrochloride, C,H,,NO,.C1H + 2H,0, crystallizes in 
scales or long, flat, lustrous prisms, which are decomposed by water. 

2374 Since it is simultaneously a phenol and a monobasic 
acid, it contains two hydrogen atoms which can be replaced by 
metals. Its salts have been investigated by Stiideler. 

When tyrosine is dissolved in warm saturated baryta water, 
the compound C,H,NO,Ba + 2H,O separates out as a heavy 
precipitate, consisting of prismatic crystals. 

Copper tyrosine, (CjH,,NO,),Cu, is a very characteristic salt, 
and is formed when copper hydroxide is added to a boiling 
aqueous solution of tyrosine. The splendid blue solution soon 
deposits dark blue needles, consisting of monosymmetric prisms, 
which are insoluble in alcohol and decompose on boiling with 
water, with separation of the black oxide.” 

Silver tyrosine, C,H,,NO,Ag, is obtained by the addition of 
silver nitrate to a boiling solution of tyrosine to which some 
ammonia has been added. It forms a sandy precipitate, con- 
sisting of short, microscopic prisms, which is tolerably stable 
towards light. A similar precipitate containing half a molecule 
of water is often formed (Erlenmeyer and Lipp), and was some- 
times observed by Stiideler. 

When a saturated ammoniacal solution of tyrosine is added 
to silver nitrate, a heavy amorphous precipitate of the salt 
C,H,NO,Ag, + H,O is formed ; it retains its water at 110° and 
deflagrates violently when further heated. . 

Nitrotyrosine, CyH,.(NO,)NO,. The nitrate of this is formed 
by dissolving tyrosine in nitric acid (Strecker). Ammonia added 
to its solution precipitates the free nitrotyrosine, which is only 
slightly soluble in hot water, and crystallizes on cooling in light 
yellow needles, which have a slightly bitter, but not acid, taste, 
and form a deep red coloured solution in alkalis (Stiideler). 

Dinitrotyrosine, C,xH,( NO,),.NO3, 1s obtained by the evaporation 
of nitrotyrosine nitrate with nitric acid ; it crystallizes in lustrous, 
golden-yellow plates, which are slightly soluble in water, readily 
in alcohol, have an acid but not bitter taste and do not combine 


1 Hoffmann, Ann. Chem. Pharm. Ixxxvii. 124; L. Meyer, ibid. exxxii. 156. 
2 Hofmeister, ibid. clxxxix. 24. 


AMIDOTYROSINE. 183 


with acids. It is a strong dibasic acid, the yellow and red salts 
of which deflagrate on heating (Stadeler). 

Amidotyrosine, Cj5H,,(NH,)NO,, was obtained by Beyer by 
the reduction of nitrotyrosine ; it is a crystalline powder, which 
is readily soluble in water and slightly in alcohol, and is a 
di-acid base. 

Tyrosinesulphonic acid, C,H,NO,.SO,H +2H,O, forms a 
starchy powder, consisting of microscopic crystals, which crystal- 
lizes from a hot aqueous solution in anhydrous, slightly soluble 
crusts. Ferric chloride produces a violet colouration in the 
aqueous solution (Stideler). 

Parahydroxy-a-phenyl-lactic acid, C,H,OH)CH,.CH(OH) 
CO,H + H,O, is formed in the preparation of tyrosine from 
amidophenylalanine when more than the calculated amount of 
sodium nitrite is employed. It crystallizes in needles, which 
_ become anhydrous at 100° and melt at 144° 

Nitrophenyl-lactyl nitrate, C,H,(NO,)CH,(CH,O.NO,)CO,H, 
is obtained by the nitration of a-phenyl-lactic acid, and crystal- 
lizes in needles. It yields paranitrobenzoic acid on oxidation, 
and is converted by reduction into paramido-a-phenyl-lactie acid, 
C,H,(NH,)CH,(CH.OH)CO,H, which is isomeric with tyrosine. 
It crystallizes in fine needles, which have an acid reaction and 
taste, melt with decomposition at 188°—189°, are more soluble in 
water and alcohol than tyrosine and do not give Piria’s reaction. 
Its hydrochloride is a crystalline mass, which is readily soluble 
in water. 

Hydroxyhydrocarbostyril, CsH,NO,. A syrupy ortho-compound 
is formed by the nitration of a-phenyl-lactic acid, which yields 
hydroxyhydrocarbostyril on reduction. It crystallizes from 
alcohol in white, lustrous plates, which sublime when heated 
in open vessels, but melt at 197°—198° when heated in capillary 
tubes. Its constitution is expressed by the following formula 
(Erlenmeyer and Lipp) : 


CH,—C.OH 
C.H | 
Pe SNEHCO 


2375 B-Phenyl-lactic acid or B-Phenyl-B-hydroxypropionic acid, 
C,H,.CH(OH)CH,.CO,H, was obtained by Glaser by the action 
of sodium amalgam on a solution of chloro- or bromo-phenyl- 
lactic acid! It is also formed when @-phenyl-8-bromopropionic 


1 Ann. Chem. Pharm, cxlvii. 78. 


278 


184 AROMATIC COMPOUNDS. 





acid is boiled with water,! and crystallizes in lustrous needles or 
prisms, which are readily soluble in cold water and in every 
relation in boiling water, melt at 93° and.decompose on further 
heating or on boiling with baryta water into water and cinnamic 
acid. Its salts have been investigated by Glaser, and also by 
Fittig and Kast.? + 
B-Phenyl-B-chloropropionte acid, C,H,.CHCLCH,.CO,H, was 
prepared by Glaser by the addition of concentrated hydrochloric 
acid to a concentrated solution of 8-phenyl-lactic acid. It is 
also formed when a solution of cinnamic acid in glacial acetic 
acid is saturated with hydrochloric acid and allowed to stand for 
some time.® It crystallizes from alcohol in nacreous plates, 
which melt at 126° and decompose into hydrochloric acid and 
cinnamic acid a few degrees above this temperature. 
B-Phenyl-8-bromopropionic acid, C,H,.CHBr.CH,.CO,H, which 
has been prepared by Glaser in a similar manner to the chlorine 
compound, is also readily formed when cinnamic acid is allowed 
to stand for several days in contact with hydrobromic acid, 
saturated at 0° (Fittig and Binder), or more rapidly when it 1s 
heated with a solution of hydrobromic acid in glacial acetic 
acid. It is very soluble in alcohol and ether, and decomposes 
when moist on gentle heating. It crystallizes from hot carbon 
disulphide in nacreous plates and from chloroform in mono- 
symmetric prisms.2 On boiling with ten parts of water, 
$-phenyl-lactic acid and cimnamic acid are formed, together 
with a little styrolene, which forms the chief product when 
sodium carbonate solution is employed. 
B-Phenyl-B-todopropionie acid, C,H,.CHI.CH,.CO,H, is formed 
by the action of hydriodic acid on @-phenyl-lactic acid (Glaser) 
and on cinnamic acid (Fittig and Binder). It separates from hot 
carbon disulphide in small, lustrous crystals, which melt with de- 
composition at 119°—120°. It behaves towards water and sodium 
carbonate solution in a similar manner to the bromine com- 
pound, but in this case styrolene is formed in predominating 
amount. 
B-Phenyl-B-amidopropionie acid, C,H;.CH(NH,)CH,.CO,H, is 
formed, together with cinnamic acid and styrolene, when the 
brominated acid is brought into ammonia at a temperature 
1 Fittig and Binder, Ann. Chem. Pharm. excv. 131. 
2 Ibid. ccvi. 26. 
3 Erlenmeyer, Ber. Deutsch. Chem. Ges. xiv. 1867. 


4 Anschiitz and Kinnicut, ibid. xi. 1221. 
5 Bodewig, ¢bid. xii. 588. 


BENZOYLACETALDEHYDE. 185 





of 0°.1 It is only slightly soluble in cold, readily in hot water, 
and crystallizes in large, monosymmetric prisms,’ melting at 
120°—121°. It does not combine with bases, but forms salts 
with acids, its hydrochloride crystallizing in lustrous prisms. On 
boiling with hydrochloric acid, it yields cinnamic acid and 
ammonium chloride. 


KETONIC ACIDS, ©,H,0.CO,H. 


2376 Benzoylacetaldehyde, C,H;.CO.CH,.CHO. When equal 
molecules of ethyl formate and acetophenone are added to an 
ice-cold solution of sodium in twenty to thirty parts of alcohol, a 
granular crystalline precipitate is gradually formed : 


C,H,.CO.CH, + CHO.0C,H, + Na0.C,H, = 
C,H,CO.CHNa.CHO + 2HO.C,H,. 


If this be dissolved in water and treated with acetic acid, the 
aldehyde is obtained as an oily, unstable liquid, the alcoholic 
solution of which produces a deep red colouration with ferric 
chloride. Copper acetate gives a light green precipitate, consist- 
ing of fine needles of (C)H,O,),Cu, which soon change into flat, 
dark green, glittering prisms. When an aniline salt is added 
to the solution of the sodium compound benzoylethidene-aniline, 
C,H;.CO.CH,.CH—NC,H, (Pt. IV. p. 140), separates out, 
and may be obtained from hot alcohol, in which it is readily 
soluble, mm small yellow plates or short prisms, melting at 
140°—141°. Similar compounds are formed with other primary 
amido-bases.? 

Benzoylacetic acid, C,H,.CO.CH,.CO,H, is formed when 
phenyl-propiolic acid is dissolved in sulphuric acid and the 
liquid poured upon ice after standing for some hours: 


C,H,.C=C.CO,H + H,O = C,H,.CO.CH,.CO,H. 


It may be more readily obtained from its ethyl ether by dis- 
solving it in dilute caustic soda, acidifying with sulphuric acid 
after twenty-four hours and extracting with ether. The acid 


1 Posen, Ann. Chem. Pharm. excv. 144. 
2 Calderon, Jahresb. Chem. 1880, 372. 
3 Claisen and Fischer, Ber. Deutsch. Chem. Ges. xx. 2191. 


186 AROMATIC COMPOUNDS. 


is left on evaporation as a crystalline mass, which crystallizes 
from benzene in small needles, melting with evolution of carbon 
dioxide at 103°—104°. It is slightly soluble in cold, more readily 
in hot water, and decomposes when strongly treated by itself or 
with sulphuric acid into methylphenylketone and carbon dioxide. 
Its alcoholic or hot aqueous solution is coloured violet by ferric 
chloride? 

Ethyl benzoylacetate, C,H,.CO.CH,.CO,C,H,, is obtained in a 
similar manner from ethyl propiolate. It may be synthetically 
prepared in the following manner. The nitrite of ethyl amid- 
acetate, NO,.NH,.CH,.CO,.C,H,, is formed by the action of 
silver nitrite on the hydrochloride, and crystallizes in trans- 
parent, colourless prisms, which soon decompose with formation 
of ethyl diazo-acetate, N,CH.CO,.C,H,, a golden yellow, volatile, 
and explosive liquid, which possesses a characteristic odour. 
When this is heated with benzaldehyde in presence of toluene, 
it combines with evolution of nitrogen and formation of ethyl 
benzoylacetate : ” 


N 
C,H,.CHO + | CH.CO,.C,H, — (,H,.CO.CH,,CO,,.0,H, + Ny. 
N 


A better yield of the ether is obtained when equal molecules 
of sodium ethylate, free from alcohol, and ethyl benzoate are 
heated on the water-bath until a compact cake has been formed ; 
this is heated for fifteen hours with an excess of ethyl acetate, 
and then treated with glacial acetic acid and water, the oil 
which separates being dried and distilled under diminished 
pressure. A little aceto-acetic ether passes over first, followed 
by unaltered ethyl benzoate and finally benzoylacetic ether, a 
small quantity of dehydrobenzoylacetic acid being left behind.? 
Ethyl benzoylacetate is also readily formed by the action of 
sodium on a mixture of ethyl benzoate and ethyl acetate.* It is 
a strongly refractive liquid, which boils with decomposition at 
268°—270°, has a pleasant smell resembling that of aceto-acetic 
ether and decomposes on boiling with dilute sulphuric acid 
into carbon dioxide, alcohol and methylphenylketone. The 


1 Baeyer, Ber. Deutsch. Chem. Ges. xv. 2705; Baeyer and Perkin, zbid. xvi. 
2125 ; Perkin, Journ. Chem. Soc. 1884, i. 170; 1885, i. 240. 

> Curtius, Ber. Deutsch. Chem. Ges. xvii. 953; Curtius and Buchner, 7bid. 
XVili. 2371. 

3 Claisen and Lowman, bid. xx. 651. 

4 Wislicenus, ibid. xx. 654. 


PARANITROBENZOYLACETIC ACID, 187 





alcoholic solution gives a violet-red colouration with ferric 
chloride. 

The hydrogen of the methylene group in ethyl benzoylacetate, 
like that in aceto-acetic ether, is replaceable by metals, alcohol 
radicals, ete. When the alkaline solution is treated with sodium 
amalgam, 8-phenyl-lactic acid is formed. — 

Sodiwm ethyl  benzoylacetate, C,H;.CO.CHNa.CO,.C,H,, 
separates out in long, silky needles, when sodium ethylate is 
added to the ether. It is insoluble in cold water, but is 
decomposed on boiling. 

Ethyl isonitrosobenzoylacetate, C,H;.CO.CC(NOH)CO,.C,H,, is 
formed when sodium nitrite and then dilute sulphuric acid are 
added to the alkaline solution of the ether. It crystallizes from 
alcohol in long needles, which melt at 120°—121° and form a 
yellow solution in alkalis. 

Paranitrobenzoylacetic acid, C,H,(NO,)CO.CH,.CO,H, is 
obtained by dissolving paranitrophenylpropiolic acid in 80—85 
per cent. sulphuric acid and allowing the solution to stand at 
35°—40° for fifteen hours. It is then poured on to ice and 
the acid extracted with ether. It crystallizes from benzene 
in microscopic needles and from hot water in four-sided 
tablets, which melt at 135° and simultaneously decompose into 
carbon dioxide and paranitro-acetophenone, the same decom- 
position being effected by boiling with water. Its alcoholic or 
warm aqueous solution gives a deep reddish brown colouration 
with ferric chloride. 

Lithyl nitrobenzoylacetate, C,H, NO,)CO.CH,.CO,.C,H,, is 
formed by passing hydrochloric acid into a mixture of the acid 
with absolute alcohol, and crystallizes in yellow needles or from 
a mixture of benzene and petroleum-spirit in transparent, mono- 
symmetric prisms, melting at 74°—76°. Its sodium compound 
crystallizes in orange-yellow needles, which have a very bitter 
taste and can be recrystallized from hot water. When nitrogen 
trioxide is passed into a solution of the ether, the isonitroso- 
compound, C,H,(NO,)CO.C(NOH)CO,.C,H;, is formed and 
crystallizes from alcohol in colourless needles, which form a deep 
yellow solution in alkalis." 

Benzoylacetonitril or Cyanacetophenone, C5H,.CO.CH,.CN, is 
formed when ethyl benzoylcyanacetate, C,H;.CO.CH(CN)CO,. 
C,H,, is boiled with water, and crystallizes in needles which 
melt at 80°5°. Its ammoniacal solution gives a precipitate of 


1 Perkin and Bellenot, Journ. Chem. Soc. 1886, i. 440. 


188 AROMATIC COMPOUNDS. 


C,H,.CO.CHAg.CN with silver nitrate, which rapidly alters in the 
light. When it is boiled with concentrated caustic potash solution 
or is allowed to stand in contact with an excess of hydrochloric 
acid, it decomposes into benzoic acid, acetic acid and ammonia. If 
its alcoholic solution be saturated with hydrochloric acid at 0°, the 
hydrochloride of benzoyl acetimido-ether, C,H;.CO.CH,.C(OC,H,) 
NH.CIH, separates out in needles. The free ether, which is 
prepared from this salt, forms needles or quadratic tablets, which 
melt at 89°5° and are converted into ethyl benzoylacetate by 
heating with alcohol and hydrochloric acid.1 

2377 Alphatoluylformic acid or Benzylglyoxylie acid, C;H;.CHg. 
CO.CO,H. When hippuric acid is heated with benzaldehyde 
and acetic anhydride, benzoylamidocinnamic acid is formed : 


CoH; C,H; 


| 
CHO CH 


sail! + H,0. 
CH,.NH.CO.C,H, C.NH.CO.C,H, 


| 
CO,H CO,H 


This is converted by the further elimination of water into the 
anhydride, which crystallizes from alcohol in yellow needles, 
melting at 164°—165°, and yields the acid again on heating to 
100° with dilute hydrochloric acid. The free acid is scarcely 
soluble in water and crystallizes in lustrous prisms resembling 
those of hippuric acid, which melt with decomposition at 225° 
and are converted into benzylglyoxylic acid by boiling with 
caustic potash solution :? 


C,H, C,H, 

CH CH, 

| + 2H,0 = | + HO.CO.C,H, + NH,. 
CNH.CO.C,H, CO 

| | 

CO,H 60,1 


It is also obtained when sodium is added to a mixture of ethyl 
oxalate with ether and ethyl phenylacetate gradually added ; the 
ethyl ether of phenyloxalacetic acid is first formed and is then 


1 Haller, Compt. Rend. ci. 1270 ; civ. 1448. 
2 Plochl, Ber. Deutsch. Chem. Ges. xvi. 2815. 


BENZYLGLYOXYLIC ACID. 189 


decomposed in the following manner by boiling with dilute 
sulphuric acid :! 


C,H; C,H; 
| | 
CH—CO,.C,H, CH, 
| +2H,0=(|  +CO,+2HO.C.H,. 
CO CO 
| | 
-CO,.C,H, CO,H 


Benzylglyoxylic acid is only slightly soluble in cold, somewhat 
more readily in hot water and readily in alcohol. It crystallizes 
from chloroform in small plates, which have a satin lustre and 
melt at 154°—155° with evolution of carbon dioxide. Its 
alcoholic solution is coloured deep green by ferric chloride and 
gives the same reaction as phenylglyoxylic acid with sulphuric 
acid and benzene containing thiophene.2 As a ketonic acid it 
forms compounds with hydroxylamine and _ phenylhydrazine ; 
water and sodium amalgam convert it into a-phenyl-lactic acid. 

Orthohydroxybenzylglyoxylic acid, C,H,(OH)CH,.CO.CO,H, is 
prepared from hippuric acid and salicylaldehyde in a similar 
manner to the preceding compound. It crystallizes from hot 
water in flat needles or prisms and gives a deep green colour- 
ation with ferric chloride. On heating with dilute sulphuric 
acid it is converted into the anhydride, Aenien has been named 
oxycumarin by Plochl and Wolfram : 


CH,—CO CEs —O0 

GH | = (i + H,O. 

*“\oH  CO0.0H Fe 20 

It crystallizes from alcohol in lustrous prisms, melting at 
152°—153°. 

Orthohydroxybenz zylglycolie acid or Salicyl-lactie acid, C,H,(OH) 
CH,.CH(OH)CO,H, is formed by the action of sodium amalgam 
ra water on the preceding compound, and is a readily colnhie 


syrup. Its salts however crystallize well. 


1 W. Wislicenus, Ber. Deutsch. Chem. Ges, xx. 589, 
2 E. Erlenmeyer, Jun. cbid. xix. 2576. 
3 Plochl and Wolfram, ibid. xviii. 1179. 


190 AROMATIC COMPOUNDS. 


PHENYLPROPENYL COMPOUNDS. 


2378 Phenylglycerol or Stycerol, C,H;.CH(OH)CH(OH)CH,. 
OH, was prepared by Grimaux from its dibromohydrin by 
heating to 150°—165° with water and a little silver acetate. It 
is a gum like mass, which has a bitter taste, dissolves readily in 
water and alcohol, is insoluble in ether and decomposes on 
heating. 

Phenylpropenyldibromohydrate or Styceroldibromohydrin, C,H. 
CHBr.CHBr.CH,.OH, is obtained by the addition of bromine to 
a cooled solution of cmnamyl alcohol in chloroform. It is readily 
soluble in alcohol and ether and crystallizes in needles or tablets, 
melting at 74°. 

Phenylpropenyl tribromide or Styceroltribromohydrin, C,H ;.CH. 
Br.CHBrCH,Br, is formed by the combination of bromine with 
cinnyl bromide or by the repeated distillation of the preceding 
compound with hydrobromic acid. It crystallizes from ether 
in tablets, which melt at 96°5°. 

Phenylpropenylacetodibromohydrin, C,H;.CHBr.CHBr.CH,.O. 
C,H,O, is the product of the action of acetyl chloride on the 
dibromohydrin and crystallizes from ether in oblique prisms, 
melting at 85°—86°.? 


PHENYLDIHYDROXYPROPIONIC ACIDS. 


2379 Phenylglyceric acid or Styceric acid, C,H,.CH(OH)CH 
(OH)CO,H, was first prepared from its ethyl dibenzoyl ether by 
heating with alcoholic potash? It is also formed when 
a-phenylchlorolactic acid, C,H,.CH(OH)CHCLCO,H, is heated 
with caustic soda solution, phenylacetaldehyde being simul- 
taneously formed (p. 9). It crystallizes from ether, in which 
it is only slightly soluble, in lustrous plates, which melt with 
decomposition at 143°—144°, 


? Grimaux, Bull, Soc. Chim. xx. 120. 2 Grimaux, loc. cit. 
* Anschiitz and Kinnicut, Ber. Deutsch. Ohem. Ges. xi. 1219 ; xii. 538. 
4 Lipp, ibid. xvi. 1287. 


PHENYLGLYCERIC ACID. 191 


Dibenzoylstycerre acid, C,H,(CH.O.CO.C,H;),CO,H, is obtained 
by heating the acid with benzoyl chloride, and crystallizes from 
benzene in small needles (Lipp). 

Ethyl dibenzoylstycerate, C,H,(CH.O.CO'C,H,),CO,C,H,, is the 
product of the action of silver benzoate on ethyl phenyldi- 
bromopropionate in presence of toluene, from which it crystallizes 
on evaporation in well developed, monosymmetric crystals. 

Paranitrostyceric acid, C,H,(NO,)CH(OH)CH(OH)CO,H, is 
formed when paranitrophenylglycidic acid is boiled with dilute 
sulphuric acid, and crystallizes from hot water in distorted plates, 
which melt at 167°—168° 

B-Phenyldichloropropionie acid, C,§H,.CHCLCHCLCO,H, was 
prepared by Glaser by the action of fuming hydrochloric acid 
on phenylchlorolactic acid,? C,H,.;CH(OH)CHCI1CO,H, while 
Erlenmeyer obtained it by passing chlorine into a solution of 
cinnamic acid in carbon disulphide.* It crystallizes in lustrous 
plates, which melt at 162°—164°, with simultaneous discoloura- 
tion, and are insoluble in water, but gradually decompose into 
carbon dioxide and a-phenylchlorethylene (p. 32) on boiling 
with water or on standing in the cold with sodium carbonate 
solution. 

B-Phenyldibromopropionie acid, C,H;.CHBr.CHBr.CO,H, is 
obtained by the action of bromine vapour on cinnamic acid,‘ as 
well as by treating phenylbromolactic acid with fuming hydro- 
bromic acid.® In order to prepare it, cinnamic acid is dissolved 
in carbon disulphide and a solution of bromine in carbon 
disulphide gradually added, the acid being thus precipitated.® It 
forms small plates or monosymmetric crystals, which readily 
dissolve in ether, melt at 195° and readily decompose slightly 
above this temperature. On boiling with water, phenylbromolac- 
tic acid, cimnamic acid, a-phenylbromethylene and carbon dioxide 
are formed. This decomposition is also brought about by cold 
sodium carbonate solution, but is delayed by an excess of this 
reagent,” 

Glaser obtained an isomeric acid in the form of a smeary 
crystalline mass by the action of bromine on hydrocinnamic 


1 Lipp, Ber. Deutsch. Chem. Ges. xix. 2645, 
2 Ann. Chem. Pharm, cxlvii. 96. 

3 Ber. Deutsch. Chem. Ges. xiv. 1867. 

4 Schmitt, dnn. Chem. Pharm. exxvii. 320. 
5 Glaser, zbid. exlvii. 91. 

8 Fittig and Binder, ibid. excv. 140. 

7 Fittig and Kast, ibid. cevi. 33. 


192 AROMATIC COMPOUNDS. 


acid. This substance decomposes on boiling with water with 
formation of phenylacetaldehyde : * 


O,H,.CH,-CBr,.CO,H -+ H,O7= 
C,H;.CH,.CHO + CO, + 2HBr. 


Ethers of Phenyldibromopropionic acid are best obtained by the 
addition of bromine to the corresponding cinnamic ethers. Like 
the acids they form well developed, monosymmetric crystals.? 


Melting-point. 
Methyl phenyldibromopropionate, C,H,Br,0,(CH,). 117° 
Ethyl phenyldibromopropionate, C,H,Br,O,(C,H,) . 69° 
Propyl phenyldibromopropionate, C,H,Br,O,(C,H,). 23° 


Phenylchlorohydroxypropionic acid or a-Phenylchlorolactie acid, 
C,H;.CH(OH)CHCLCO,H + H,0, is formed by the addition of 
hypochlorous acid to cinnamic acid.2 In order to prepare it, 
chlorine is passed into a cooled solution of cinnamic acid and 
sodium carbonate, or, more advantageously, a solution of sodium 
hypochlorite is added to one of potassium cinnamate, a-pheny]l- 
chlorethylene being simultaneously formed.4 It is tolerably 
soluble in cold, in every proportion in boiling water, and crystal- 
lizes in six-sided plates, which lose their crystal-water over 
sulphuric acid and then melt at 104°. 

Orthonitrophenylehlorolactic acid, C,H,INO,)CH(OH)CHCL 
CO,H, is prepared by passing chlorine into an alkaline solution 
of orthonitrocinnamic acid, and is precipitated by petroleum-ether 
from its solution in benzene as a crystalline mass, which melts at 
119°—120 and is converted into indol by treatment with sodium 
amalgam or caustic soda and ferrous sulphate (p. 36). 

a-Paranitrophenylchlorolactie acid, C,H,(NO,)CH(OH)CHBr. 
CO,H, is obtained in a similar manner from paranitrocinnamic 
acid, and crystallizes from water in rhombic plates, melting at 
165°° Its barium salt can be boiled with water without 
undergoing decomposition. 

B-Paranitrophenylehlorolactic acid, C,H,(NO,)(CHCI)CH(OH) 
CO,H, is formed by the combination of hydrochloric acid with 


1 Erlenmeyer, Ber. Deutsch. Chem. Ges. xiii. 308. 

2 Anschiitz and Kinnicut, loc. cit. 

3 Glaser, Ann. Chem. Pharm. exlvii. 79. 

4 Erlenmeyer and Lipp, zbid, ccxix. 183. 

> Baeyer, Ber. Deutsch. Chem. Ges, xiii. 2261. 

6 Beilstein and Kuhlberg, dann. Chem. Pharm. clxiii. 42. 


a-PHENYLBROMOLACTIC ACID. 193 


paranitrophenylglicidic acid, and forms small crystals, melting at 
167°—168°. The barium salt decomposes on boiling with water 
into carbon dioxide, barium chloride and paranitrophenylacetal- 
dehyde (p. 10).! 

a-Phenylbromolactie acid, C,H,.CH(OH)CHBr.CO,H + H,0, is 
formed when phenyldibromopropionic acid is boiled with water, 
and by the addition of hypobromous acid to cinnamic acid. It 
crystallizes from hot water in plates, which lose their crystal- 
water on heating and then melt at 125°? 

B-Phenylbromolactic acid, C,H,.CHBr.CH(OH)CO,H, is pre- 
pared by the action of fuming hydrobromic acid on styceric acid 
and has not been fully described.* 

a-Phenyliodolactic acid, C,H;.CH(OH)CHI.CO,H, is obtained 
by bringing cinnamic acid into an aqueous solution of iodine 
chloride. It separates from benzene in large crystals, which melt 
at 137°—139° with decomposition.! 

2380 Phenylglycidic acid, C,H,.C,H,0.CO,H, is formed when 
a-phenylchlorolactic acid or the corresponding bromine compound 
is treated with alcoholic potash (Glaser) : 

Soeur 7 i ENG 
CO,H.CHBr CO, H.CH” 


Acids precipitate it as an oily liquid, which solidifies at 0° to 
minute, lustrous scales and decomposes at the ordinary tempera- 
ture into phenylacetaldehyde and carbon dioxide (Erlenmeyer). 

Orthonitrophenylglycidic acid, C,H,(NO,)C,H,O.CO,H, is pre- 
pared by the action of alcoholic potash on orthonitrophenyl- 
lactic acid,® or by boiling the latter with sodium carbonate 
solution.® It crystallizes in flat needles and melts with decom- 
position at 110°, a portion being thus converted into indigo-blue 
(Baeyer). 

Paranitrophenylglycidic acid was obtained by Erlenmeyer as a 
by-product in the preparation of paranitrochlorophenyl-lactic 
acid; it is also formed by the action of alcoholic potash on the 
latter, and crystallizes in splendid tablets, which have a satin 
lustre and melt at 186°—188°. It combines with hydrochloric 
acid to form §-paranitrophenylchlorolactic acid.’ 


1 Lipp, Ber. Deutsch. Chem. Ges. xix. 2646. | 

2 Glaser, Ann. Chem. Pharm. cxlvii. 84; Erlenmeyer, Ber, Deutsch. Chem. Ges. 
xiii. $310; xv. 2159. 

8 Lipp, zbid. xvi. 1290. 4 Erlenmeyer and Rosenhek, ibid. xix. 2464. 

5 Baeyer, ibid. xiii. 2262. § Lipp, zbed. 2649. 

7 Lipp, Ber. Deutsch. Chem. Ges. xix. 2648. 


194 AROMATIC COMPOUNDS. 


Atroglyceric acid, C,H;.C(OH)(CH,.OH)CO,H, is formed, 
together with acetophenone, when a-phenyldibromopropionic 
acid is treated in the cold with sodium carbonate solution + or 
when its nitril is decomposed with hydrochloric acid? It 
separates from hot water in small needles, united to warty 
aggregates, melting at 146°. 

Atroglyceronitril, C,H;.C(OH)(CH, OH)CN, is formed by the 
combination of benzoylmethyl alcohol, C,H,;.CO.CH,.OH, with 
hydrocyanic acid, and crystallizes from ether in long, thick 
needles. 

a-Phenyldibromopropionic acid or Dibromohydratropic acid, 
C,H,;.CBr(CH,Br)CO,H, is obtaimed by adding bromine to 
atropic acid in solution in carbon disulphide, from which it 
separates in long, silky needles, while it crystallizes from hot 
chloroform in small, pointed needles, united to druses, which 
melt at 115°—116°. On boiling with water it decomposes into 
carbon dioxide, hydrobromic acid and acetophenone? The 
formation of the latter is analogous to that of phenylacetalde- 
hyde from phenylbromolactic acid, the first product being 
the alcohol, C,H,.C(OH)—CH,, which then passes into the 
ketone.4 


PHENYLPROPYLENE O,H,.CH—CH.CH,. 


2381 This hydrocarbon, which is also termed allylbenzene, is 
formed in small quantity, together with phenylpropyl alcohol, 
by the action of sodium amalgam and hot water on cinnyl 
alcohol,’ C,H,.CH—CH.CH,.OH, and also, together with toluene 
and probably ethyl iodide, when the alcohol is heated to 
180°—200° with hydriodic acid: 


(1) C,H,.CH—CH.CH,.OH + 2HI = 
C.H,,CH—CH.CH, + H,0 + I, 


(2) C,H,.CH—CH.CH, + 3HI = 
C,H,.CH, + CH,.CH,I + I,. 


1 Fittig and Kast, Ann. Chem. Pharm. cevi. 29. 
2 Plochl and Bliimlein, Ber. Deutsch. Chem. Ges. xvi. 1290. 
3 Fittig and Wurster, Ann. Chem. Pharm. excv. 159. 
4 Erlenmeyer, Ber. Deutsch. Chem. Ges. xiii. 309. 
a Fittig and Kriigener, ibid. vi. 214 ; Riigheimer, Ann. Chem. Pharm. elxxii. 


PHENYLPROPYLENE. 195. 


Phenylpropylene may also be obtained by heating phenyl- 
crotonic acid, C,H;.CH—C(CH,)CO,H, or better by combining 
it with hydrobromic acid and decomposing the product with 
carbonate of soda! It is also formed by the distillation of 
secondary phenylpropyl bromide,? by the action of alcoholic 
potash on secondary phenylpropyl chloride? and by the treat- 
ment of ethylphenylcarbinol with phosphorus pentachloride.* 

Itis a strongly refractive, pleasant-smelling liquid, which boils 
at 174°—175° and has a sp. gr. of 0°9180 at 15°. On boiling with 
sodium it passes into a polymeric modification, which boils above 
330° and probably corresponds to distyrolene (Errera), Chojnacki, 
by heating benzene with zinc dust and allyliodide, obtained an 
isomeric hydrocarbon, which boils at 155°° and is probably the 
true allylbenzene, C,H,;.CH,.CH—CH,,. 

Phenylpr opylene Se ide C, 1s CHBr.CHBr. CH,, is formed by 
the combination of the Te ceocas ban with bromine,® and has also 
been obtained from propylbenzene (p. 153). It crystallizes from 
alcohol in long needles, melting at 66°5°. 

Phenylnitropropylene, C,H;.CH—C(NO,)CH,, is obtained, 
accompanied by resinous products and benzamide, when benz- 
aldehyde is heated to 130°—140° with nitroethane and zinc 
chloride. It crystallizes from petroleum-spirit in yellow, lustrous 
needles or transparent prisms, which melt at 64° and volatilize 
readily in steam; the vapour smells like nutmeg. It com- 
bines with weamins to form the dibromide, C, H, .CHBr.CBr 
(NO,)CH,, which crystallizes in transparent Pastis prisms, 
melting at 77°—78'5°. It is converted by fuming nitric acid 
into the following compounds, which can readily be separated by 
means of alcohol. 

Orthonitrophenylnitropylene, C,H, NO.)CH—C(NO,)CH,, is 
readily soluble in alcohol and crystallizes in light yellow plates, 
melting at 76°—77.° It yields orthonitrobenzoic acid on 
oxidation. 

Paranitrophenylnitropropylene forms yellow needles, which are 
only slightly soluble in alcohol, melt at 114°—115° and are 
oxidized to paranitrobenzoic acid by potassium permanganate.’ 


1 Tiemann, Ber. Deutsch. Chem. Ges. xi. 617. 

2 Perkin, Journ. Chem. Soc. 1877, ii. 660. 

3 Radziszewski, Jahresber. Chem. 1874, 393. 

4 Errera, Ber. Deutsch. Chem. Ges. xviii. Ref, 149. 
5 Compt. Rend. \xxvi, 1413. 

6 Riigheimer, Radziszewski, Perkin, loc. cit. 

7 Priebs, Ann. Chem. Pharm. ccxxy. 319. 


196 AROMATIC COMPOUNDS. 





2382 Anol or Allylphenol, C,H,;.C,H,.OH, was first prepared 
by Ladenburg by heating its methyl ether or anethol to 
200°—230° with caustic potash. It crystallizes im small plates, 
which melt at 93°, become yellow in the air and then change into 
a brownoil. This alteration takes place partially on distillation, 
even in an atmosphere of carbon dioxide, and also on heating 
with dilute acids. A portion of the phenol is always oxidized to 
parahydroxybenzoic acid during its preparation. 

Anethol, C;H;.C,H,(OCH,), occurs, accompanied by a larger or 
smaller quantity of a terpene, C,)H,,, in the essential oil of the 
seeds of Anethum foeniculum, Pimpinella anisum, Artemisia 
dracunculus, and Illicium anisatum, and is deposited in plates 
when these oils are cooled.2 Perkin, who names it parallylanisoil, 
obtained it by heating methylparahydroxyphenylcrotonic acid.? 

OE ea /OCEs 
AEG = CoH + CO,. 
CH—CH.CH,.CO,H CH-—CTECH. 


It has a more pleasant but fainter odour than oil of anise, melts 
at 21°, boils at 232° and has a sp. gr. of 0°989 at 28°. On boiling 
with hydriodic acid it yields methyl iodide, while the anol, which 
is simultaneously formed, is converted into a resinous mass‘ It 
is oxidized by chromic acid solution to anisic acid and acetic 
acid. On heating with phosphorous chloride, chloranethol, 
C,H,(OCH,)C,H,Cl, is formed. This substance boils at 258°, 
and on boiling for some time with alcoholic potash 1s converted 
into allylenephenyl methyl ether, C,5H,(OCH,)C=C.CH,, which 
is a liquid, boiling at 240° and possessing a faint but pleasant 
odour (Ladenburg). 

Anethol readily forms polymeric modifications. 

Metanethol, (C,)H,,0)n, is formed by heating anethol with 
zinc chloride,’ and crystallizes from glacial acetic acid or ether 
in very thin needles, which melt at 132°. It commences to 
sublime at 115°, is volatile in superheated steam and boils with 
decomposition above 300°. It is attacked by bromine with 
evolution of hydrobromic acid.® 


1 Ann. Chem. Pharm. Suppl. viii. 87. 
2 Cahours, zbid. xli. 75 ; Laurent, ibid. xliv. 313; Gerhardt, zbid. xliv. 318 ; 
Teas 

3 Journ. Chem. Soc. 1877, ii. 669. 

4 Ladenburg and Leverkus, Ann. Chem. Pharm. cxli. 260. 

© Gerhardt, Journ. Prakt. Chem. xxxvi. 167. 

6 Perrenond, Ana. Chem. Pharm. clxxxvii. 63. 


EUGENOL. 197 


Anisoin, (C,)>H,,0)n, is obtained by the action of sulphuric 
acid or phosphoric acid (Cahours), antimony trichloride, tetra- 
chloride (Gerhardt), benzoyl chloride? or a solution of iodine 
in potassium iodide* on anethol. It crystallizes from ether 
in small needles, which melt at 140°—145°. It is resolved 
by distillation into dsanethol and volatile metanethol, the latter 
being a liquid, which boils at 232°5° and has a sp. gr. of 
09706 at 18°. It is converted into anisoin by sulphuric 
acid, 

Tsanethol is a thick, yellowish liquid, which remains unaltered 
at 380° and is converted into anisoin by agitation with sulphuric 
acid.’ 

2383 Hugenol, CH,0.C,H,(OH)C,H,, forms the chief con- 
stituent of the essential oil of cloves (Hugenia caryophyllata), 
of allspice (Hugenia pimenta),* of the leaves of the cinnamon 
tree (Cinnamomum zeylanicum), of canella bark (Canella alba),o— 
and probably of the Brazilian cinnamon (Dycipelliwm caryophyl- 
latum),’ and also occurs in that of the leaves of Jlliciwm 
religuosum. 

Bonastre found that oils of cloves and allspice form crystal- 
line compounds with bases, and Dumas then analysed the first 
of these and obtained the formula C,,H,,0,.° Liebig and Etling, 
‘however, found that it is a mixture of a terpene, C,,H,,, with 
a substance which combines with bases and was called by 
them ewgenic acid (Nelkensiure).® This substance, was subse- 
quently recognized as a phenol. Eugenol is also formed by the 
action of sodium amalgam and water on coniferyl alcohol?!® 
(p. 205). 

In order to separate it from oil of cloves, three parts of this 
are shaken up with a solution of one part of caustic potash in 
ten parts of water, the insoluble terpene removed and _ the 
eugenol liberated from the alkaline solution by hydrochloric 
acid, washed with water and rectified! It isa strongly refractive 
liquid, which becomes brown in the air, has the characteristic 

1 Kraut and Uelsmann, Jowrn. Prakt. Chem. Ixxvii. 490. 

2 Rhodius, Ann. Chem. Pharm. \xv. 230. 

3 Kraut and Schlun, Jahresb. Chem. 18638, 552. 


4 Bonastre, Ann. Chim. Phys. xxxv. 274. 
5 Stenhouse, 4nn. Chem. Pharm. xcv. 103; Schaer, Ber. Deutsch. Chem. Ges. 


xv. 2624. 6 Wohler, zbzd. xlvii. 234. 
7 Gmelin’s, Organ. Chem. iv. 200. 8 Ann. Chem. Pharm, ix. 65. 
9 Ibid. ix. 68. 


10 Tiemann, Ber. Deutsch. Chem. Gres. ix. 418. 
11 Erlenmeyer, Zeztschr. Chem. 1866, 430; Wassermann, dnn, Chem. Pharm. 
clxxix. 369. 


198 AROMATIC COMPOUNDS. 


smell and burning taste of cloves, boils with slight decom- 
position at 247°5° and has a sp. gr. of 1°:0799 at 0°, and of 
1:068 at 18°. It is a stronger antiseptic than phenol, and can 
be taken in small doses to the extent of 3 grms. in twelve 
hours without producing noteworthy effects. Larger quantities 
cause giddiness and headache. It is found in the urine as 
eugenolsulphuric acid, which readily decomposes with liberation 
of eugenol.? 

The alcohol solution is coloured blue by ferric chloride; it 
reduces ammoniacal silver solution, but not Fehling’s solution, 
and when brought in contact with dry silver oxide ignites and 
burns brilliantly. Nitric acid oxidizes it to oxalic acid, while 
acetic acid and carbon dioxide are formed by the action of 
chromic acid,? and it is converted into vanillin by potassium 
permanganate.* On fusion with caustic potash, it yields proto- 
catechuic acid,® and is converted into a resin by heating with 
hydriodic acid, methyl iodide being also formed.® 

Its salts have been investigated by Bonastre, von Briining,’ 
and Williams.® 

Methyleugenol, C,H,.C,H,(0CH,),, is formed by the action of 
methyl iodide on sodium eugenate,® and is a liquid, which boils 
at 244°—245° 1° and is oxidized to dimethylprotocatechuic acid 
by potassium dichromate and glacial acetic acid. 

Hithyleugenol, C,H;.C,H,(OCH,)OC,H,, is prepared by heating 
eugenol with ethyl bromide and caustic potash solution. It is 
an aromatic liquid, which possesses a faint smell of cloves, is 
strongly refractive, boils at 254° and is partially converted by 
distillation into a polymeric modification, which crystallizes from 
alcohol in plates, melting at 125° and subliming at a higher 
temperature. It is oxidized by chromic acid to methylethyl- 
protocatechuic acid and acetic acid. 

Cahours has also prepared the following ethers: ? 


1 De Regibus, Ber. Deutsch. Chem. Ges. xx. Ref. 485. 

2 Bottger, Jowrn. Prakt. Chem. \xxvi. 241. 

3 Wassermann, Ann. Chem. Pharm. clxxix. 372. 

4 Erlenmeyer, "Ber. Deutsch, Chem. Ges. ix. 273. 

> Hlasiwetz and Grabowsky, Ann. Chem, Pharm. cxxxix. 96. 
6 Erlenmeyer, Zeitschr. Chem. 1866, 430. 

7 Ann. Chem. Pharm. civ. 204. 

8 Ibid. evii. 241. 

9 Grabe and Borgmann, <bid. clviii. 282. 

10 Matsmoto, Ber. Deutsch. Chem. Ges. xi. 128. 

i Cahours, Compt. Rend. xlvi. 220; Wassermann, Ann. Chem. Pharm. clxxix. 


2 Ber, Deutsch. Chem. Ges. x. 237 ; Jahresb. Chem. 1877, 580. 


ETHYLEUGENOL. 199 





of Boiling-point. 
Isopropyleugenol, C,H,(OCH;,)OCH(CH,), . . 252°—254° 
Propyleugenol, C,H,(OCH,)OC,H, . . . . . 263°—265° 
Isobutyleugenol, C,H,(OCH,)OC,H, . . . . 272°—2'74° 


Amyleugenol, C,H,(OCH,)OC,H,, . . . . . 283°—285° 
Hexyleugenol, C,H,(OCH,)OC,H,,. . . . . 296°—300° 
Allyleugenol, C,H,(OCH,)OC,H, ... . . 267°—270° 
Melting-point. 

Ethylene-eugenol, (CH,0C,H,O),C,H,, prisms 89° 
Propylene-eugenol, is Oc, H.0).0,.0, Cie 

LECASE. Ve 02 SS ee nee ae nee A 56°—58° 
Trimethylene-eugenol, (CHC OO, H ONC es 

rhomb, prisms .. . 82°5° 


Acetyleugenol, CjH,(OCH;)0.CO.CH,, is formed when eugenol 
is boiled with acetic anhydride, and is a crystalline mass, which 
melts at 30°—31°, boils at 270° and is oxidized by potassium 
permanganate to acetalphahomovanillic acid (p. 25). 

Benzoyleugenol, CjH,(OCH,)0.CO.C,H,, is obtained by heating 
eugenol with benzoyl chloride,? and crystallizes on the gradual 
evaporation of its alcoholic solution in large, transparent, 
vitreous, monosymmetric prisms, melting at 69°—70°. Chromic 
acid oxidizes it to benzoylvanillic acid.* 

Hugenolglycolie acid, C,H,(OCH;)OCH,.CO,H, is prepared by 
the evaporation of a mixture of eugenol, chloracetic acid and 
caustic soda solution, and crystallizes from hot water in long, 
silky needles, which melt at 80°—81°.4 

Iso-eugenol, CH,0.C,H,(0H)C,H,, is formed when homoferuliic 
acid, C,H,(OH)(OCH;)CO,H, is heated in a current of carbon 
dioxide, and is a strongly refractive liquid, the smell of which 
resembles that of eugenol, but can easily be distinguished from 
it. It boils at 258°—262°, and has a sp. gr. of 1:080 at 16°; its 
alcoholic solution is coloured light green by ferric chloride. 

Benzoyliso-eugenol forms crystals, which melt at 159°—160°.° 

2384 Meta-eugenol or Allylresorcinol methyl ether is obtained 
by carefully heating methyl-@-methylumbellic acid, C,H,(OH) 
(OCH,)C(CH,)—CH.CO,H, and is a thick, pleasant-smelling 


1 Nagai and Tiemann, Ber. Deutsch. Chem. Ges. x, 201. 

2 Cahours, Ann. Chem. Pharm, eviii. 321. 

3 Tiemann and Kraaz, Ber. Deutsch. Chem. Ges. xv. 2067. 
4 Saarbach, Jowrn. Prakt. Chem. [2], xxi. 158. 

5 Tiemann and Kraaz, Ber. Deutsch. Chem. Ges. xv. 2064. 


279 


200 AROMATIC COMPOUNDS. 


liquid, which boils at 245°—250° and dissolves in caustic soda 
but not in sodium carbonate solution." 

The constitutions of the phenol ethers here described are 
shown by the following formule : 


Anethol. Eugenol. Iso-eugenol. Meta-eugenol. 
N 


vi aS es, 


“a ee | fee 
ie rs) Locks € yo Bs 
6CH, OH OCH, OCH,. 


Olivil, C,,H,,O;, is the crystalline constituent of the resin of the 
wild olive (Part IV. p.314), and forms a thick vapour on heating 
and has a pleasant odour resembling those of benzoin and cloves, 
which is employed in Italy for the fumigation of sick rooms. In 
order to obtain the olivil, the resin is extracted with ether and 
the residue treated with boiling alcohol. The olivil, which 
separates on cooling, is washed with cold dilute alcohol and 
recrystallized from alcohol. It forms white needles, which are 
odourless and have a sweetish, bitter taste, melt at 120° and 
solidify to an-amorphous mass, which forms a strongly-electrified 
powder on trituration. This mass melts at 70°, but after re- 
crystallization from alcohol regains the original melting-point. 
It crystallizes from hot water in stellate groups of prisms, which 
contain one molecule of water. It is readily soluble in alkalis 
and precipitates the metals from solutions of gold chloride and 
silver nitrate. On dry distillation it yields an oily liquid, to 
which Sobrero has given the name of pyro-olivilie acid.’ It has 
the composition and properties of eugenol and is either identical 
with this or iso-eugenol. When olivil is heated with hydriodic 
acid, a carbonaceous mass is formed and a mixture of methyl 
and ethyl iodides distils over. The latter is undoubtedly a 
decomposition product of the allyl group, so that olivil must be 
looked upon as eugenol in which one hydrogen atom has been 
replaced by the group U,H,O,, the constitution of which has 
not yet been determined, 

2385 Safrol, C,,H,,O,, is the chief constituent of sassafras- 
oil, which is contained in the root of the American cinnamon 
tree (Sassafras officinalis), and is extracted in the United States 

1 Pechmann and Cohen, zbid. xvii. 2132. 
2 Ann. Chem. Pharm. liv. 67- 


3 Amato, Ber. Deutsch. Chem. Ges. xi. 1251. 
4 St. Evre, Ann. Chem. Pharin. lii. 396. 


SAFROL. 3 201 


by distillation with water. This oil contains 90 per cent. of 
safrol, about 10 per cent. of safrene, C,,H,,, and a very small 
amount of a phenol, which gives a bluish green colouration with 
ferric chloride! Safrol also occurs in the oil of the camphor 
tree and is identical with shzkomol, which occurs, together with 
eugenol and shikimene, C,,H,,, which is probably safrene, in the 
ethereal oil of the leaves of the Japanese star anise (ilictwm 
religiosum) or shikimino-ki.? 

In order to obtain it pure, the fraction of sassafras-oil, which 
boils between 228°—235°, is cooled to — 25°, at which tempera- 
ture the safrol is deposited in strongly refractive, mono-symmetric 
crystals,? melting at + 8°, It has a pleasant aromatic odour, boils 
at 232°, is insoluble in alkalis and is not attacked by sodium. 

Tournefort discovered in 1698 that oil of sassafras is ignited 
by fuming nitric acid, and safrol itself has been found to detonate 
violently with the concentrated acid. If safrol, however, be 
heated with the dilute acid, it takes a red colour, which was 
observed by Bonastre, and a red-coloured resin is deposited, oxalic 
acid being also formed.* It is oxidized by a dilute solution of 
potassium permanganate to carbon dioxide, formic acid, propionic 
acid and piperonylic acid (Pt. IV. p. 355).5 It is therefore, like 
anethol and eugenol, a derivative of allylbenzene : 





Anethol, Eugenol. Safrol. 
OCH, OH O 
CH C.H,ZOCH, oH,Zo> Cis 

C,H, \C,H, \C,H, 


It is worthy of note that the fruit of Zlicium anisatum 
contains anethol, while eugenol and safrol occur in the leaves 
of Lllicowm religiosum, and are also found in various members 
of the allied family of Lauraceae; again, the root of the 
American cinnamon and the wood of the camphor tree contain 
safrol, while the leaves of the true cinnamon contain eugenol. 

The fruits of Zdlicitum religioswum and I. anisatum also con- 
tain protocatechuic acid and shikiminie acid, C,H,,O,, which is a 
crystalline powder, melting at 178°—180° It .is monobasic, 
is converted into protocatechuic acid by fusion with potash and 


1 Grimauxand Ruotte, bcd. clii. 88 ; Fliickiger and Hanbury, Pharmacographia, 
2nd Ed. 538. 

2 Hijkmann, Recweil Trav. Chim. Pays-Bas. iv. 32. 

3 Arzruni, Jahresbr. Chem. 1876, 910. 

4 J. Schiff, Ber. Dewtsch. Chem. Ges. xvii. 1935. 

> Hijkmann, loc. cit. ; Poleck, Ber. Deutsch. Chem. Ges. xix. 1094. 


202 AROMATIC COMPOUNDS. 


yields ordinary phenol on the distillation of its calcium salt. 
It appears therefore to be a tetrahydrotrihydroxybenzore acid, 
C,H,(OH),CO,H. 

2383 Asaron, C,,H,,O3, was discovered in 1814 by Gorz in 
the root of Asarabacca (Asarwm ewropacwm), and obtained by 
the distillation of the root with water. He gave it the name of 
Asarabacca-camphor, and noticed that it had a sharp, camphor- 
like smell and taste and acted as an emetic. Subsequent in- 
vestigations have shown that these properties are due to the 
admixture of an ethereal oil. Asaron was analysed by Blanchet 
and Sell,? and afterwards by Schmidt,’ who also investigated it 
crystallographically ; its correct formula was however first given 
by Rizza and Butlerow, who determined its vapour density and 
were thus enabled to ascertain its constitution. 

Asaron crystallizes in various combinations of the mono- 
symmetric system, is odourless, has a faintly biting taste, melts 
at 59°, boils at 296° and can be distilled in small quantities 
without undergoing decomposition. It dissolves readily in 
alcohol, ether, &c., and also to some extent in hot water, 
from which it crystallizes in delicate needles and small 
plates. It unites with bromine to form the crystalline com- 
pound, C,,H,,Br,O.. 

On oxidation it yields the aldehyde, C,,H,,O,, as the first 
product, accompanied by acetic acid, oxalic acid and carbon 
dioxide. It forms long, silky crystals and melts at 114°. The 
acid, C,,H,.0,, which is derived from this, crystallizes in 
needles, melts at 148° and boils at about 300°. Neither of these 
substances behave as unsaturated compounds; if they or asaron 
itself be heated with hydriodic acid, methyl iodide is formed 
in considerable quantity, and when the acid is distilled with 
slaked lime, an oily liquid, C,H,,O., is obtained, which boils at 
245°—248°, and gives three molecules of methyl iodide when 
heated for a long time with hydriodic acid, from which it follows 
that it is the methyl ether of trihydroxybenzene. The acid is 
therefore a trimethoxybenzoic acid, (CH,O),C,H,CO,H, and 


asaron has probably the following constitution : 


CH,O 


UH oNc, Ia WR Elo Ole eleby 
CHO 
1 Hijkmann, Ber. Deutsch. Chem. Ges, xviii, Ref. 281 ; ee. ¥ Ret: 67. 
2 Ann. Chem. Pharm. vi. 297. 3 bid. liii. 156. 


4 Ber. Deutsch. Chem. Ges. xvii. 1159 ; xx. Ref. 222. 


PHENYLALLYL COMPOUNDS. 203 


According to this view the acid stands in the same relation 
to asaron as veratric acid to methyleugenol or anisic acid to 
anethol. 


PHENYLALLYL COMPOUNDS. 


2387 Phenylallyl alcohol, C,H;.CH—CH — CH,.OH. Simon 
found in 1839 that the styracin, which was discovered by 
Bonastre in liquid styrax (p. 27), is converted by boiling with 
caustic soda solution into cinnamic acid and an oily liquid, which 
he named styragone.' Toel repeated these researches, making 
use of purified styracin, and instead of a liquid obtained a 
crystalline substance, which he named styrone, assuming that 
styracin is a compound of similar constitution to the fats and 
consists of cinnamic acid and styryl oaide, the latter of which 
combines with water on saponification to form styrone, just as 
glycerin is formed from lipyl oxide (Pt. IL. p. 344)” Strecker 
determined the correct formula of styrone and showed that it 
stands in the same relation to cinnamic acid as alcohol to acetic 
acid, in other words that it is the alcohol of cinnamic acid.? This 
was confirmed by Wolff, who converted it into the latter by 
oxidation.* 

Further investigations have shown that cinnamy] alcohol, which 
is also called cinnyl or styryl alcohol, is phenylallyl alcohol, and 
that Simon’s styragone was a mixture of this with phenylpropyl 
alcohol.® 

Cinnyl alcohol occurs, probably as cinnamate, in Peru balsam 
pete LV pa 

In order to prepare it, styrax is distilled with sodium carbonate 
solution until styrolene no longer passes over, the aqueous 
solution containing sodium cinnamate removed, the residue 
distilled with caustic potash and the cinnyl alcohol separated 
from phenylpropyl alcohol by the fractional distillation of the oily 
distillate. Pure styracin may also be distilled with caustic 
potash ; the cinnyl alcohol crystallizes out of the distillate, while 


rm = 


Ann. Chem. Pharm. xxxi. 265. 
Ibid. xx. 1, | & Ibid. Ixx. 11. 4 Ibid. 1xxv. 297. 
The name styryl alcohol is liable to be confused with styrolyl alcohol (p. 6), 
and since the radical of cinnamic acid is designated cinnamy]l, it is most convenient 
to employ the name cinnyl alcohol, which was proposed by Henry Watts. 

6 Riigheimer, Ann. Chem. Pharm, cvxxii. 22; V. Miller, zbid. exxxviii. 184. 

7 Delafontaine, Zettschr. Chem. 1869, 156. 


an 


204 AROMATIC COMPOUNDS. 


any remaining in the solution is precipitated with salt or 
extracted with ether. 

Cinnyl alcohol crystallizes in long, thin needles, which melt 
at 33°, and have a pleasant smell of hyacinths; it boils 
at 250, is tolerably soluble in water, readily in alcohol and 
ether and is oxidized to cinnamaldehyde by platinum black.? 
It is converted into phenylpropyl alcohol by the action of 
sodium amalgam on its warm aqueous solution, a little allyl- 
benzene being simultaneously formed. If, however, an amalgam 
containing 15 per cent. of sodium be employed with only a little 
water, the mixture being heated on the water-bath, it is resolved 
into styrolene and methyl alcohol : ? 


C,H,.CH—CH.CH,.0OH + 2H = C,H,.CH—CH, + CH,,.OH. 


On heating to 180°—200° with concentrated hydriodic acid, 
it 1s reduced to allylbenzene; toluene is formed at the same 
time, the amount increasing with the duration of the experiment, 
and ethyl iodide is also probably among the products (see p. 194).3 

Cinnyl alcohol combines with bromine to phenyldibromopropyl 
alcohol or styceryl dihydrobromide, C,H;.CHBr.CHBr.CH,.OH. 

The following cinnyl compounds have been investigated by 
~Ramdohr.* 

Cinnyl ethyl ether, C,5H,.CyH,.0.C,H,, is a heavy liquid, which 
boils at a high temperature. 

Dicinnyl ether, (C,H;.C,H,),0, is formed when the alcohol is 
heated with boron trioxide, and is a thick, oily liquid, which has 
an odour resembling that of cinnamon and partially decomposes 
on distillation. 

Cinnyl chloride, C,H;.C,H,Cl, is a yellowish, oily liquid, 
the smell of which resembles those of oil of anise and oil of 
cinnamon; it decomposes on distillation even under diminished 
pressure, 

Cinnyl todide, C,H;.C,H,I, 1s a heavy, aromatic-smelling liquid, 
which has a burning taste and decomposes even on distillation 
with water. 

Cinnylamine, C,H,.C;H,.NH,, forms small, colourless crystals, 
which have a very bitter taste and readily fuse to an oil, which 
volatilizes even at 100°, forming a vapour which has an alkaline 
reaction. 


1 Strecker, Ann. Chem. Pharm. xciii. 370. 

2 Hatton and Hodgkinson, Journ. Chem. Soc. 1881, i. 319. 
3 Tiemann, Ber. Deutsch. Chem. Ges. xi. 671. 

4 Jahresber. Chem. 1858, 446. 


CONIFERIN. 205 


2388 Coniferyl alcohol, CH,0.C,H,(0H)CH—CH.CH,.OH, is 
obtained by the action of emulsion on its glucoside, coniferin, 
suspended in 10 parts of water. The mixture is allowed to 
stand for 6—8 days at 25°—36°, and the whole repeatedly 
extracted with ether. The residue after the evaporation of 
the ether is then purified by recrystallization from ether. 

Coniferyl alcohol crystallizes in prisms, which melt at 74°, 
are scarcely soluble in cold, only slightly in hot water and 
more readily in alcohol. It is immediately polymerized by 
dilute acids to an amorphous substance, which is less soluble in 
alcohol and ether and softens at 150°—160°. Chromic acid 
oxidizes coniferyl alcohol to vanillin and acetaldehyde ; it yields 
protocatechuic acid on fusion with potash, and is reduced to 
eugenol by the action of sodium amalgam and water. As a 
phenol it forms crystalline compounds “with the alkalis. On 
heating with hydriodic acid, methyl iodide, ethyl iodide and 
bromocatechol are formed, accompanied by a resinous mass : 


/OH 
C,H;—CH—CH.CH,.OH + 4HI = 
NOCH, 
OH 


CHC OH, + CH,I + CH,.CH,I + I, + H,0. 


This decomposition corresponds to that which cinnyl alcohol 
undergoes when heated with hydriodic acid. 

Comferin, CH,0.C,H,(C,H,.0OH)O.C,H,,0, + 2H,O, occurs 
in the cambium sap of the conifers. Its preparation has 
already been described (see vanillin, Pt. IV. p. 345). It is 
slightly soluble in cold, more readily in hot water and alcohol, but 
is insoluble in ether, and crystallizes in stellate or rosette-shaped 
groups of pointed needles, which become anhydrous at 100° 
and melt at 185°. Its solution has a faintly bitter taste and is 
laevoorotatory. It forms a red solution in concentrated sul- 
phuric acid, which deposits an indigo-blue resin on the addition 
of water. If it be moistened with phenol and concentrated 
sulphuric acid, it rapidly becomes coloured a deep blue, the 
change being almost instantaneous in the sunlight. Pine wood 
can thus be employed to detect phenol, or the presence of 


1 Tiemann and Haarmann, Ber. Deutsch. Chem. Ges, vii. 608 ; viii. 1127 ; xi. 


667. 
2 Hartig and Kubel, Zeiischr. Chem. 1866, 339. 


206 AROMATIC COMPOUNDS. 


coniferin may be ascertained in the various pines, which contain 
it both when fresh and after being preserved for a considerable 
period, 

2389 Cubebin, C,)H,,O3, occurs in cubebs,! which are the 
unripe fruits of Piper Cubeba, and separates from their ethereal 
extract when this is preserved for some time.” In order to 
prepare it, the powdered cubebs are freed from ethereal oil by 
distillation with water and are then extracted with boiling 
alcohol, the solvent distilled off and the solution purified by 
recrystallization® It forms tasteless and odourless needles, 
which are scarcely soluble in water and melt at 125°4 On 
heating with caustic potash it is decomposed into protocatechuic 
acid, acetic acid and carbon dioxide, and it is oxidized by 
alkaline permanganate solution to piperonylic acid,’ so that it 
has the following constitution : 


0 
CHC | >CyH, CH=CH.CH, OF 


Nitrocubebin, C,,H)(NO,)O3, was obtained by Weidel by the 
action of nitrogen dioxide on an ethereal solution of cubebin ; 
it crystallizes in light yellow needles, which form a purple-violet 
solution in caustic potash. 


PHENYLACRYL-COMPOUNDS. 
CINNAMALDEHYDE, C,H,.CH—CH.CHO. 


2390 Cinnamon (Cinnamomum zeylanicum) and cassia bark or 
bastard-cinnamon, which is derived from various species of Cinna- 
momum growing in China and the Indies and are mentioned in 
the Pentateuch and by Herodotus and other authors, weré con- 
sidered as the most valuable of spices and were eagerly sought 
after by the earliest travellers in the East. The essential oils 
which are contained in them and in cloves, were first prepared 


1 Souberan and Capitaine, Ann. Chem. Pharm. xxxi. 190; Schmidt, Ber. 
Deutsch. Chem. Ges. x. 190. 

* Schuck, Rep. Pharm. [2], i. 218; Engelhardt, ibid. iii, 1. 

3 Steer, Ann. Chem. Pharm. xxxvi. 331, 

4 Weidel, Wien. Akad. Ber, xxiv. 377, 

5 Pomeranz, Monatsh. Chem. vill. 466. 


PHENYLACRYL COMPOUNDS. 207 


in the middle of the sixteenth century by Valerus Cordus, who 
stated that these belong to the few essential oils, which are 
heavier than water.! 

Trommsdorff observed in 1780 that water which has been 
distilled over cinnamon deposits a crystalline salt on standing, 
while other chemists found that crystals gradually separate out 
of oil of cinnamon, and these were mistaken for benzoic acid until 
Dumas and Peligot, in 1834, observed that they are a new acid, 
which they named cinnamic acid (acide cinnanvique). They 
also found that oil of cinnamon bears the same relation to 
it as oil of bitter almonds or benzoyl hydride to benzoic 
acid, and therefore gave it the name of cinnamyl hydride 
(hydrure de cinnamyle).2 It also occurs in the essential oil of 
the so-called flowers of cinnamon,’ the unripe fruits of bastard- 
cinnamon. It is remarkable that the leaves of the cinnamon 
tree contain eugenol, but no cinnamaldehyde (p. 197). 

Cinnamaldehyde was first synthetically prepared by Chiozza, 
who had found that cinnamic acid decomposes into acetic and 
benzoic acids on fusion with potash, and therefore endeavoured 
“to prepare cinnamic acid or cinnamyl hydride inversely from 
the atomic groups contained in benzoic and acetic acids.” To 
this end he saturated a mixture of acetaldehyde and benzalde- 
hyde with hydrochloric acid and heated; oily drops separated 
out and on distillation he obtained cinnamaldehyde, preceded 
by a little unaltered benzaldehyde : 4 


C.H,;.CHO + CH,.CHO = C,H,.CH=CH.CHO + H,0. 


It may be very easily prepared by allowing a mixture of 10 
parts of benzaldehyde, 15 parts of acetaldehyde, 900 parts of 
water and 10 parts of a 10 per cent. solution of caustic soda 
to stand for 8—10 days at a temperature of 30°, the whole 
being frequently agitated and finally extracted with ether.’ 

Piria obtained it by the distillation of a mixture of calcium 
cinnamate and calcium formate.® 

Oil of cinnamon contains, in addition to cinnamaldehyde, a 
hydrocarbon, which is probably a terpene, C,,H,,; these may be 


1 Fliickiger and Hanbury, Pharmacographia, 2nd Ed. 219. 

2 Ann. Chem. Pharm. xiv. 50; Ann. Chim. Phys. lvii. 305. 
3 Mulder, 4nn. Chem. Pharm. xxxiv. 147. 

4 Ann. Chem. Pharin. xevii. 350. 

5 Peine, Ber. Deutsch. Chem. Ges. xvii. 2117. 

6 Ann. Chem. Pharm, ¢. 104. 


208 AROMATIC COMPOUNDS. 


separated, as discovered by Dumas and Peligot, by bringing the 
oil into contact with concentrated nitric acid, the compound 
(C,H,O,),N,O, being formed, which separates out in long, 
oblique, rhombic prisms or small plates, and is decomposed by 
water into nitric acid and the free aldehyde. This characteristic 
compound has probably the following constitution : 


C.H,.C,H,—ONO, 
Chico: 
C.H,.C,H, ONO, 


Bertagnini obtained pure cinnamaldehyde by agitating oil of 
cinnamon with 3 or 4 volumes of a concentrated solution of acid 
potassium sulphite; the compound O,H,.C,H,.CH(OH)SO,K 
separated in scales, which were dried, washed with alcohol, 
again dried and finally decomposed with dilute sulphuric acid? 
According to Peine, an alcoholic solution of 50 parts of oil of 
cinnamon is agitated with 90 parts of a 50 per cent. solution of 
acid sodium sulphite, and the compound, after washing with 
alcohol, decomposed with sulphuric acid, 40 cb. cm. of this, 
diluted with an equal volume of water, being employed for 
every 100 cb. cm. of the sulphite solution. The aldehyde is 
then distilled with steam, the distillate extracted with ether 
and, after the evaporation of the ether, fractionated under 
diminished pressure.’ 

Cinnamaldehyde is a colourless, very pleasant smelling liquid, 
which decomposes on distillation at the ordinary pressure, but 
boils without alteration at 130° under a pressure of 830—40 mm. 
(Peine). When it is added to a solution of a salt of rosaniline, 
which has been decolourized by sulphurous acid, a deep yellow 
colouration is produced, which soon passes into violet-red.4 

Hydrocinnamide or Cinnamidenediamine, (C,H;.CH—CH. 
CH),N,, was prepared by Laurent by the action of ammonia 
on oil of cinnamon.’ In order to prepare it, pure cinna- 
maldehyde is dissolved in 3—4 volumes of absolute alcohol and 
dry ammonia passed into the cooled solution. After twenty- 
four hours the crystalline paste is washed with dilute alcohol, 
dissolved in alcohol and treated with an excess of hydrochloric 
acid. The salt C,,H,,N,CIH + 3H,O separates out and is 

1 Ann. Chem. Pharm. c. 104. ; Mulder, Joc. cit. 
2 Ibid. \xxxv. 271. 
3 Ber, Deutsch. Chem. Ges. xvii. 2109. 


4 Schmidt, Ber. Deutsch. Chem. Ges. xiv. 1849. 
5 Journ. Prakt. Chem. [1], xxvii. 309. 


ORTHONITROCINNAMALDEHYDE. 209 


then dissolved in an additional quantity of alcohol and pre- 
cipitated in tabular crystals by the addition of ether. If am- 
monia be added to the hot alcoholic solution, hydrocinnamide 
crystallizes out on cooling in white needles, melting at 106°. 
It is also formed when aqueous ammonia is repeatedly agitated 
with an ethereal solution of cinnamaldehyde during several 
weeks (Peine), 

Cinnamaldoxime, C,H,.CH—CH.CH—NOH, is formed by 
the action of hydroxylamine on the aldehyde, and crystallizes 
from hot water or benzene in very fine needles, melting at 
134°—136°4 

Cinnamidene-aniline, C,H,.CH—CH.CH—NG,H,, is obtained 
by heating cinnamaldehyde with aniline. It crystallizes from 
hot alcohol in yellow plates, melting at 109°, and is converted into 
phenylquinoline, C,,H,,N, by heating with hydrochloric acid? 

Cinnamidenephenylhydrazone, C,H..CH—CH.CH—N.NHOC,H,, 
is formed when cimnamaldehyde and phenylhydrazone or their 
alcoholic solutions are mixed, and crystallizes in yellow needles 
or plates, melting at 166°° 

Lromocinnamaldehyde or Phenylbromacrylaldehyde, C,H;.CBr 
—CH.CHO. Cinnamaldehyde combines with bromine to form 
phenyldibromopropionaldehyde, C,H;.CHBr.CHBr.CHO, a crys- 
talline substance, which has a characteristic odour and causes a 
flow of tears. It readily decomposes with formation of phenyl- 
bromacrylaldehyde, which crystallizes from alcohol in thick 
tablets and from ether in large, very lustrous, monosymmetric 
prisms, melting at 72°—73°. Its phenylhydrazone forms broad, 
lustrous plates which turn brown in the air, become dark 
coloured at 122° and melt at 129°—130°, It is converted into 
a-bromocinnamic acid by oxidation. 

2391 Orthonitrocinnamaldehyde or Orthonitrophenylacrylalde- 
hyde, C,H,(NO,)CH—CH.CHO, was first synthetically prepared 
by Baeyer and Drewsen from orthonitrobenzaldehyde ; this body 
combines with acetaldehyde to form the aldehyde of orthonitro- 
8-phenyl-lactic acid, which loses water on boiling with acetic 
anhydride : ° 


C,H,(NO,)CH(OH)CH,.CHO=C,H,(NO,)CH—CH.CHO+H,0. 


1 Bornemann, Ber. Deutsch. Chem. Ges. xix, 1512. 

2 Dobner and v. Miller, zbid. xvi. 1664 ; Peine, bid. xvii. 2117. 
3 Fischer, zbid. xvil. 575; Peine, loc. cit. 

4 Zincke and v. Hagen, Ber. Deutsch. Chem. Ges. xvii. 1814. 

5 Ibid. xvi. 2205. 


210 AROMATIC COMPOUNDS. 


Orthonitrocinnamaldehyde is also formed, together with the 
para-compound, when 25 grms. of cinnamaldehyde are gradually 
run into a well stirred and well cooled mixture of 500 grms. 
of sulphuric acid and 20 grms. of saltpetre. On pouring into 
water, the nitrated aldehydes separate out in flakes. The mixture 
is recrystallized from hot alcohol and is then redissolved in boil- 
ing absolute alcohol and heated with an equal volume of acid 
sodium sulphite solution. The compound of the para-nitro- 
aldehyde partially separates out on cooling and is completely — 
precipitated by adding salt and allowing the solution to stand 
for twenty-four hours. The liquid is then filtered, diluted with 
10 volumes of water and the ortho-compound precipitated with 
concentrated sulphuric acid, the last traces being extracted with 
benzene.! | 

Orthonitrocinnamaldehyde crystallizes from hot alcohol in 
fine needles, which melt at 127° and are readily soluble in boil- 
ing water. Its hydrazone forms Bordeaux-red needles, melting 
at 157°5°. 

Paranitrocinnamaldehyde was prepared by Gohring by boiling 
the aldehyde of paranitro-@-phenyl-lactic acid,2 and is also 
obtained by the decomposition of its sodium sulphite compound. 
It crystallizes from alcohol or hot water in long needles, 
which melt at 141°—142°. Its phenylhydrazone forms orange- 
red crystals, melting at 180°—181° (Diehl and Eimhorn). 

Metanitrocinnamaldehyde is formed when 100 grms. of meta- 
nitrobenzaldehyde are dissolved in two litres of alcohol and 
treated with four litres of water, 35 grms. of acetaldehyde and 
70 grms. of 10 per cent. caustic soda solution. The precipitate 
is filtered off after twelve hours, washed with ether and recrystal- 
lized from hot dilute alcohol. It is thus obtained in long, thin 
prisms, while it crystallizes from hot water in fine needles, 
melting at 116°. Its phenylhydrazone forms garnet-red tablets, 
melting at 160°? 

a-Nitrophenylbromacrylaldehyde, C,H,(N O,)C Br=CH.CHO, is 
obtained together with the following compound by the nitration 
of phenylbromacrylaldehyde (Zincke and v. Hagen). The two 
isomerides are separated by recrystallization from a mixture of 
benzene and petroleum-spirit, in which the a-compound is the 
less soluble. It forms yellowish, foliaceous needles or more 


1 Diehl and Einhorn, Ber. Deutsch. Chem. Ges. xviii. 2235. 
* [be RVI Os 
3 Kinkelin, 7bid. xviii. 483. 


CINNAMIC ACID. 211 








compact crystals, which melt at 136°. Its hydrazone is ruby- 
red and melts at 154°. Reducing agents convert the a-compound 
into a red base, the hydrochloride of which forms almost black 
crystals. 

B-Nitrophenylbromacrylaldehyde crystallizes in long, yellowish, 
transparent needles, melting at 96°—97°. Its hydrazone forms 
golden-yellow plates, which melt with decomposition at 134°. 

y-Nitrophenylbromacrylaldehyde is prepared by the addition of 
bromine to metanitrocinnamaldehyde and decomposition of the 
product with hot sodium acetate solution. It crystallizes from 
alcohol in long, fine needles, melting at 90°, and its hydrazone 
forms golden-yellow plates, which melt at 120° (Kinkelin). 


CINNAMIC ACID OR 8-PHENYLACRYLIC ACID, 
C,H,,CH—CH.CO,H. 


2392 This acid was for a long period mistaken for benzoic 
acid, but after Dumas and Peligot had shown that a character- 
istic acid is formed by the oxidation of oil of cinnamon, it was 
found that the acid contained in liquid styrax,! Peru balsam? 
and Tolu balsam is also cinnamic acid.’ 

It occurs in styrax partly in the free state and partly as 
styracin or cinnyl cinnamate, while the balsams contain the free 
acids accompanied by the benzyl ether of cinnamic and benzoic 
acids. Both these acids have also been found in Sumatra 
benzoin ;° cinnamic acid also occurs, according to Eijkman, in 
the leaves of the Japanese garden plant Hnkyanthus japonicus,® 
and has been found by Heckel and Schlagdenhauffen in Globu- 
laria Alypum and Globularia vulgaris." 


1 Buchner, Rep. Pharm. lv. 210; Fremy, Ann. Chem. Pharm. xxx. 330; 
Plantamour, 7bid. xxx. 341 ; Simon, 7dbid. xxxi. 265; Marchand, Journ. Prakt. 
Chem. xvi. 60. 

2 Delafontaine, Zeitschr. Chem. 1869, 156; Kraut, Ber. Deutsch. Chem. Ges. 
li. 180. 

8 Simon; Fremy, Joc. cit. ; Deville, Ann. Chem. Pharm. xliv. 804 ; Kopp, 
ibid. 1x. 269; Busse, Ber. Deutsch. Chem. Ges. ix. 830. 

4 Aschoff, Jahresber. Chem. 1861, 400. 

5 Kolbe and Lautemann, Ann. Chem. Pharm, exix. 136. 

6 Ber, Deutsch. Chem. Ges. xx. Ref. 66, 

7 Ann. Chim. Phys. [5], Xxviil. 67. 


212 AROMATIC COMPOUNDS. 


Bertagnini obtained it synthetically by heating benzaldehyde 
with acetyl chloride to 120°—130°: ? 


O.H,.CHO + CH,COCl = C,H,.CH=CHCOCI + H,0 = 
C,H,.CH—CH.CO.OH + HCl. 


It is also formed when benzaldehyde and glacial acetic acid are 
heated together to 16° in presence of hydrochloric acid or zine 
chloride.” 

It may also be obtained, acccording to Swarts, by the action 
of carbon dioxide on a mixture of a-bromostyrolene, C,H,CH—= 
CHBr, and sodium. Erlenmeyer, who repeated this experiment, 
only obtained a mixture of phenylpropiolic acid, C,H,.C=C.CO,H, 
and phenylpropionic acid. The first of these, which was then 
unknown, was probably mistaken by Swarts for cinnamic acid.? 

Perkin has found that the acids of the cimnamic series may 
be synthetically prepared by heating benzaldehyde with the 
anhydride of a fatty acid and the anhydrous sodium salt of the 
fatty acid. In order to prepare cinnamic acid in this way, a 
mixture of 1 part of sodium acetate, 2 parts of benzaldehyde 
and 3 parts of acetic anhydride is boiled for a day or heated 
for five to six hours in a sealed tube at 180°. The product is 
boiled with water to volatilize any unaltered benzaldehyde, and 
the impure cinnamic acid, which crystallizes out on cooling, is 
washed and dissolved in hot sodium carbonate solution; the 
liquid is allowed to cool and is then filtered in order to remove 
an oily impurity, the cmnamic acid being precipitated with 
hydrochloric acid and finally crystallized from dilute alcohol. 

The formation of the cinnamic acid may be expressed by the 
following equation : 


CH,CO. C,H, CH=CH.Co 
Of SO + 2H,0. 


2C,H,.CHO + -- 
os CH,CO” 0,H,CH=CH.co” 


According to this, cinnamic anhydride is formed and is then 
decomposed by the boiling with water. When acetic anhydride 
and benzaldehyde are heated together, however, no cinnamic 
acid is formed, benzidene diacetate, C,H,CH(OCO.CH,), (Pt. IV. 
p. 187), being in this case the product. What then is the 
function of the sodium acetate? Perkin has found that it can 

1 Ann. Chem. Pharm. c. 125. 


2 Schiff, Ber. Deutsch. Chem. Ges. iii. 412. 
3 Ibid, xvi. 152. 


CINNAMIC ACID. 213 


be replaced by butyrate or valerate without affecting the produc- 
tion of cinnamic acid; these salts therefore appear either to act 
merely as dehydrating agents or to bring about a decomposition 
of the benzidene diacetate which is first formed. 

Perkin succeeded in preparing the homologues of cinnamic 
acid by employing other anhydrides. Fittig on the other hand 
found that when benzaldehyde is heated with acetic anhydride 
and the sodium salt of a higher fatty acid, an acid is formed, 
which must be looked upon as a condensation product of this 
higher acid with benzaldehyde, and concludes from this that 
the anhydride has merely a dehydrating action and that the 
sodium salt enters into the reaction, cinnamic acid being 
therefore formed according to the following equation :2 


C,H,.CHO + CH,.CO,Na = C,H,CH—CH.CO,Na + H,0. 


Since, however, the lower acids are stronger acids than 
their higher homologues, it appears more probable that the 
sodium salts of the latter are decomposed by the anhydrides of 
the lower acids, the final product being always a condensation 
product of benzaldehyde with the higher acid, whether this 
is originally present in the form of anhydride or sodium salt. 

Slocum and Fittig have now ascertained that when benzalde- 
hyde is heated with acetic anhydride and sodium butyrate to 
100°, phenylangelic acid is the only product, while cinnamie 
acid is also formed ata higher temperature. Fittig, therefore, 
maintains his view that the reaction takes place between the 
benzaldehyde and the sodium salt, while, on the other hand, Perkin 
has shown that isobutyric anhydride is formed when acetic 
anhydride and sodium isobutyrate are heated together. Fittig 
has also proved that in many cases an hydroxy-acid is first formed 
and is then converted into an acetyl derivative by the acetic 
anhydride. Phenyl-lactic acid would thus be the first product 
of the action of sodium acetate on benzaldehyde : 


Jou 
C,H,CHO + CH,;.CO,Na = CoH;.CH 
CH,.CO,Na 


This acid or its acetyl derivative, acetylphenyl-lactic acid, 
would then decompose at a higher temperature into cinnamic 
1 Journ. Chem, Soc. 1877, i. 838. 


2 Ber. Deutsch. Chem. Ges. xiv. 14. 
3 Tiemann and Kraaz, ibid. xv. 2061. 


214 AROMATIC COMPOUNDS. 


acid and water or acetic acid. Fittig and Slocum were unable 
to prove the formation of either of these acids, since they are 
converted. into cinnamic acid at a temperature below that at 
which benzaldehyde acts upon sodium acetate.’ 

That they are actually formed at one stage of the reaction is 
proved by the fact, that when sodium isobutyrate is employed, 
phenylhydroxypivalic acid, C,H,.CH(OH)C(CH,),CO,H, which 
is incapable of simple conversion imto cinnamic acid, is formed. 
The accuracy of this view is also confirmed by the following 
reaction. When benzaldehyde is heated with acetic anhydride, 
benzidene diacetate is formed, as has already been mentioned. 
If this be heated with sodium acetate, cinnamic acid is formed, 
and can be even more readily obtained by heating benzidene 
chloride with sodium acetate,? the diacetate being however the 
first product, as is also the case in Perkin’s reaction. 

In order to explain the conversion of this substance into 
cinnamic acid, we must assume that in the presence of sodium 
acetate it passes into the metameric acetylphenyl-lactic acid, 
which immediately undergoes decomposition : + 


/9L0.CH, 0.00.CH, 
C,H,.CH = C,H, CHS 
\0.C0.CH \CH,.CO.OH — 


O,H, CH—CH.CO.OH + HO.CO.CH,. 


Cimnamic acid is also formed when benzaldehyde is heated to 
140° with malonic acid :° 


C,H,.CHO + CH,(CO,H), = 
C.H,.CH—CH.CO,H + CO, + H,0O. 


Cinnamic acid was formerly prepared from liquid styrax, but is 
now manufactured by the method discovered by Caro, which 
can also be used for the preparation of substituted cinnamic 
acids by the employment of substitution products of benzidene 
chloride, ® 

Properties—Cinnamic acid dissolves in 3500 parts of water 
at 17°; it is much more readily soluble in boiling water and 
crystallizes from it in lustrous plates, while it separates from 


1 Ann. Chem. Pharm. ecexxvii. 48. 

2 C. Konig, Ber. Deutsch. Chem. Ges. xv. 266. 
3-H. Caro, Private communication. 

4 Perkin, Journ. Chem. Soc. 1886, i. 317. 

> Michael, Amer. Chem. Journ. v. 205. 

6 Ber, Deutsch. Chem. Ges. xv. 969. 


THE CINNAMATES. 215 


alcohol in monosymmetric prisms, melting at 133°1 It sublimes 
in a similar manner to benzoic acid but somewhat less readily, 
is volatile in steam and boils at 300°—304", but partially decom- 
poses on continued boiling into styrolene and carbon dioxide. 
It undergoes the same decomposition when heated with lime 
or baryta, benzene being also formed.’ It also yields benzene 
in considerable quantity on fusion with caustic soda,* while it is 
resolved into benzoic and acetic acids when caustic potash is 
employed.* Oxidizing agents convert it first into benzalde- 
hyde, so that it can in this way be readily distinguished from 
benzoic acid. When taken internally it undergoes oxidation 
and appears in the urine as hippuric acid.® It is converted into 
hydrocinnamic acid by sodium amalgam and water. 

2393 Zhe Cinnamates. These salts, which resemble the ben- 
zoates, have been chiefly investigated by Herzog’ and Kopp.§ 
The salts of the alkali metals combine with cinnamic acid to 
form so-called acid salts. 

Acid sodium cinnamate, C,H,NaO, + C,H,0,, was prepared 
by Perkin by heating benzaldehyde in a sealed tube with acetic 
anhydride and sodium acetate. It forms a white, opaque mass and 
is decomposed by water into the normal salt and cinnamic 
acid. 

Calcium cinnamate, (C,H,O,),Ca + 3H,O0, crystallizes in 
needles, which dissolve in 608 parts of water at 17°5° (Kraut). 

Barium cinnamate, (C,H,0,),Ba + 2H,O, is even less soluble 
than the calcium salt and crystallizes from hot water in plates. 

The soluble salts give a yellow precipitate with ferric chloride. 
It may be distinguished from benzoic acid and atropic acid (p. 
233) by the fact that its soluble normal salts give an immediate 
precipitate with manganese chloride. 

Methyl cinnamate, C,H,0,(CH,), forms crystals, which have 
a very pleasant odour, melt at 33°4° and boil at 263°.° 

Ethyl cinnamate, C,H,O,(C,H,) is a pleasant smelling liquid, 
boiling at 271° (Anschiitz and Kinnicutt), which is contained in 
liquid styrax. 


1 Kraut, Ann. Chem. Pharm. exlvii. 112. 

2 Howard, Jahresb. Chem. 1860, 303. 

3 Barth and Schreder, Ber. Deutsch. Chem, Ges. xii. 1257. 
Chiozza, Ann. Chem. Pharm. Ixxxvi. 264; Kraut, doe. cit. 
Stenhouse, zbid. lv. 1. 

Erdmann and Marchand, zbid. xliv. 344. 

Arch. Pharm, xx. 159. 

8 Jahresb. Chem. 1861, 418. 

9 Anschiitz and Kinnicutt, Ber. Deutsch. Chem. Ges. xi. 1220. 


280 


Na ue 


216 AROMATIC COMPOUNDS. 


Benzyl cinnamate or Cinnamein, C,H,0,(C,H,), is a consti- 
tuent of Peru balsam and is formed when sodium cinnamate is 
heated with benzyl chloride.’ It crystallizes in prisms, which 
melt at 39°, 3 

Cinnyl cinnamate or Styracin, C,H,O,(C,H,), is the chief 
constituent of liquid styrax; it 1s best isolated from this by 
filtering hot through a cloth and triturating the filtrate with 
cold petroleum-spirit. One-half of the liquid is then distilled off 
and the solution filtered from the precipitate, which consists of 
the ethyl cinnamate, phenylpropyl cinnamate and a portion of the 
styracin. The clear liquid deposits the styracin on standing in 
dazzling white, fascicular crystals, which melt at 44° (v. Miller). 

When it is treated in ethereal solution with bromine, phenyl- 
dibromopropyl cinnamate, C,5H,O,(C,H,Br,), is the first product. 
It crystallizes in small plates and is converted by zinc and hydro- 
chloric acid into phenylpropyl cinnamate, C,H,O,(C,H,.C,H,), 
which is thus obtained pure. It is a liquid, which decomposes 
on distillation. 

The tetrabromide, C,H,Br,O,(C,H,Br,), is formed by the 
further action of bromine on styracin as a white, resinous 
mass, which is reduced to phenylpropyl hydrocinnamate when its 
ethereal solution is agitated with sodium amalgam and water.? 

Cinnamyl oxide or Cinnamic anhydride, (Cy,H;.C,H,.CO),O, 
was prepared by Gerhardt by the action of cinnamyl chloride on 
anhydrous potassium oxalate. It is almost insoluble in cold 
alcohol and separates from hot alcohol as a crystalline powder, 
which melts at 127°. 

Mixed anhydrides, which are very unstable, are formed when 
sodium cinnamate is treated with acetyl chloride’ or benzoyl 
chloride.® 

Cinnamyl chloride, C;H;.C,H,.COCI, is formed by the action 
of phosphorus pentachloride on cinnamic acid; it distils at 
170°—171° under a pressure of 58 mm. almost without decom- 
position, and solidifies on cooling to a yellowish, crystalline mass, 
which melts at 35—36°4 

Cinnamamide, C,H,.C,H,.CO.NH,, is obtained by treating the 
chloride with ammonia ; it crystallizes from hot water in plates, 
which melt at 141°5° 

1 Grimaux, Zeitschr. Chem. 1869, 157. 

2 vy. Miller, Ann. Chem. Parm. elxxxix. 343. 3 [bid. |xxxvii. 76. 


* Rostoski, ibid. elxxviii. 214; Claisen and Antweiler, Ber. Deutsch. Chem. 
Gres, xiii. 2124, 


© Rossum, Jahresb. Chem. 1866, 362. 


CHLOROCINNAMIC ACIDS, 217 


Cinnamonitril, C,H;.C,H,.CN, is formed when the amide is 
heated with phosphorus chloride? and when cinnamic acid is 
distilled with lead thiocyanate.2 It is a liquid, which boils at 
254°—255° and solidifies to a mass, which melts at 112. 

Phenylallenylamidoxime, C,;H;.CH—CH.C(NOH)NH,, is the 
product of the combination of the nitril with hydroxylamine 
and crystallizes from dilute alcohol in pointed prisms, melting 
at 93°83 

Distyrenie acid, C,,H,,O,, is prepared by heating 1 part of 
cinnamic acid with 4 parts of sulphuric acid and 4 parts of 
water for some time: 


2C,H,0, = C,,H,,0, + CO, 


Distyrolene is also formed in this reaction. 

Distyrenic acid is an amorphous mass, which is slightly soluble 
in water, readily in alcohol, softens when heated and becomes 
completely liquid at 50°. It can be distilled almost without 
decomposition, forms amorphous salts and is oxidized to benzoic 
acid by chromic acid solution.‘ 


HALOGEN DERIVATIVES OF CINNAMIC ACID. 


2394 The hydrogen both of the nucleus and the side-chain 
of cinnamic acid may be replaced by halogens, The compounds 
of the latter class will be described under phenylhydroxyacrylic 
acid. Those which contain halogens in the nucleus have been pre- 
pared from amidocinnamic acid by means of the diazo-reaction ; 
they crystallize for the most part badly, in contradistinction to 
the corresponding derivatives of hydrocinnamic acid.° 


CHLOROCINNAMIC AcIDs, C,H,ClC,H,.CO,H. 


Melting-point, 
Ortho, indistinct, yellow crystals. . . . 200° 
Meta, indistinct, yellowish needles . . . 167° | 
Para, yellowish, crystallme mass. . . . 24(0°—242° 


1 Rossum, Zeitschr. Chem. 1866, 362. 

2 Kriiss, Ber, Deutsch. Chem. Ges. xvii. 1768, 

3 Wolff, ibid. xix. 1507. 

4 Erdmann and Fittig, Ann. Chem. Pharm. cexvi. 179. 

5 Gabriel, Ber. Deutsch. Chem, Ges, xv. 2291; Gabriel and Lact ibid, 
Xvi. 2036, 


218 AROMATIC COMPOUNDS. 








BROMOCINNAMIC Acips, C,H,Br.C,H,.CO,H. 


Melting-point. 
Ortho, fine, flat needles . ...... £Q11°—213° 
Meta, long, faintly yellow needles . . . 178°—179° 
Para, yellow or brownish needles . . .  251°—253° 


IopocinNAMic Acips, C,H,1.C,H,.CO,H. 


Ortho, crystals... . . gel ee ee 
Meta, melts with etowrron at . . 181°—182° 
Para, indistinct crystals; decomposes 

without fusion. 


These compounds are converted into the corresponding 
derivatives of hydrocinnamic acid by heating with hydriodic 
acid and amorphous phosphorus. 

Fluocinnamic acid, C,H, ¥.C,H,.CO,H, is obtained in a similar 
manner to fluorbenzoic acid and crystallizes in white, lustrous 
needles, which are readily soluble in water and_ volatilize 
without decomposition on heating.’ 


NITROCINNAMIC ACIDS, C,H,(NO,)C,H,.CO,H. 


2395 Beilstein and Kuhlberg found that the cinnamonitric 
acid or nitrocinnamic acid, which had been prepared by 
Mitscherlich by the nitration of cinnamic acid,? and which is 
also formed by the action of nitric acid on cinnyl alcohol, is the 
para-compound and that the ortho-derivative is simultaneously 
formed. In order to prepare it, 1 part of cinnamic acid is 
dissolved in 5 parts of nitric of sp. gr. 1°48, the solution poured 
into snow and the precipitate repeatedly extracted with boiling 
alcohol, which dissolves the ortho-acid and a portion of the 
para-compound. Their ethyl ethers are then prepared by passing 
a current of hydrochloric acid through the solution, and are 


1 Griess, Ber. Dewtsch. Chem. Gres. xviii. 960. 

2 Jowrn. Prakt. Chem. [1] xxii. 192 ; Soe ee ibid. xli, 425. 
3 Wolff, Ann. Chem. Pharm. lxxv. 303. 

4 Ibid. ebeiit. 126. 


a a 


NITROCINNAMIC ACIDS. 219 





‘separated by means of cold alcohol, in which that of the ortho- 
acid is readily soluble while the para-ether is almost insoluble.! 
The separation may be more rapidly effected by converting the 
crude product directly into the ethers, separating these by alcohol 
and hydrolyzing with sodium carbonate solution.’ 

Orthonitrocinnamic acid is also formed when _ orthonitro- 
benzaldehyde is boiled with acetic anhydride and sodium acetate ® 
and when orthonitrobenzidene chloride is heated with sodium 
acetate. It crystallizes in needles, which melt at 240°, are 
insoluble in water and only dissolve slightly in cold alcohol. Its 
solution in concentrated sulphuric acid becomes coloured blue 
on standing or when gently warmed.®? Chromic acid solution 
oxidizes it to orthonitrobenzoic acid. 

If it be brought mto bromine or submitted to the action of 
bromine vapour, combination takes place, but does not occur 
when the operation is carried on in the sunlight. The ortho- 
nitrophenyldibromopropionic acid, C,H,(NO,)CHBr.CHBr.CO,H, 
which is thus obtained, crystallizes from benzene in short 
needles, which melt with decomposition at about 180°, a trace 
of indigo being formed. It forms a colourless solution in 
alkalis, which becomes yellow after some time or on heating, 
orthonitrophenylpropiolic acid and then isatin being formed. 
When the aqueous solution is heated with caustic soda solution, 
a small amount of crystallized indigo blue is obtained, while indol 
is formed when the acid is heated with zinc dust and caustic soda 
(Baeyer). 

Kthylorthonitrocinnamate, C,H,0NO,)C,H,.CO,.C,H;, forms 
thin needles or rhombic crystals, melting at 44° (Baeyer). 

Metanitrocinnamic acid is obtained by boiling metanitro- 
benzaldehyde with acetic anhydride and sodium acetate. It 
crystallizes from alcohol in fine needles and is precipitated from 
an ammoniacal solution by sulphuric acid as a snow-white 
crystalline powder, melting at 196°—197°.° It yields metanitro- 
benzoic acid on oxidation. ) 

Hihyl metanitrocinnamate crystallizes from alcohol in long, 
pointed needles, melting at 78°—79°. 


1 Morgan, Jahresb. Chem. 1877, 788. 

2 Miller, Ann. Chem. Pharm. cexii. 124. 

3 Gabriel and Meyer, Ber. Deutsch. Chem. Ges. xiv. 830. 

4 Bad. Anilin- und Sodafabrik, zbid. xv. 969. 

5 Baeyer, Ber. Deutsch. Chem. Ges. xiii. 2257. 

® R. Schiff, cbid. xi. 1782 ; Tiemann and Oppermann, ibid. xiii. 2060 ; Fried- 
lander and Lazarus, Ann. Chem. Pharm. ecxxix. 2338. 


220 AROMATIC COMPOUNDS. 





Paranitrocinnamie acid is only slightly soluble in boiling 
alcohol, from which it crystallizes in prisms, melting at 288°} 
Chromic acid oxidizes it to paranitrobenzoic acid. 

Ethyl paranitrocinnamate forms very fine needles, which melt 
at 138°5° and are almost insoluble in cold alcohol and ether. 


NH, 
AMIDOCINNAMIC ACIDS, 0,1, 
\oH = CH.CO,H. 


2396 Orthamidocinnamic acid cannot be prepared by the 
reduction of orthonitrocmmnamic acid with ammonium sulphide 
or tin and hydrochloric acid, since its inner anhydride, carbo- 
styril, is always formed. It is readily obtained however by 
treating the solution of the nitro-acid in caustic baryta with 
ferrous sulphate.? 

In order to prepare it, 150 grms, of orthonitrocinnamic acid 
and 2,100 grms. of crystallized barium hydroxide are dissolved 
in 30 litres of hot water, 1,400 grms. of ferrous sulphate are 
added and the whole heated to 95°—100° for two hours. Carbon 
dioxide is then passed through the liquid and the filtrate con- 
centrated ; barium amidocinnamate crystallizes out and a second 
crop is obtained by evaporation of the mother-liquor. The 
total quantity is dissolved in 750 cb. cm, of hot 4 per cent. 
hydrochloric acid, the barium precipitated with sodium sulphate, 
the solution boiled up with animal charcoal, filtered and neu- 
tralized with caustic soda and finally treated with sodium 
acetate, which precipitates the larger portion of the amido-acid, 
the remainder crystallizing out on cooling.’ 

Orthamidocinnamic acid forms a yellow, crystalline powder, 
or needles, which melt at 158°—159° with evolution of gas. 
It is tolerably soluble in hot water and alcohol, forming solu- 
tions which have a strong bluish green fluorescence. 

When it is dissolved in hot, dilute hydrochloric acid, the 
hydrochloride, C,H,NO,.C1H, crystallizes on cooling im warty 
masses of hard, compact prisms. 


1 Drewsen, Ann. Chem. Pharm. cclxii. 150. 
2 Tiemann and Oppermann, Ber. Deutsch. Chem. Ges, xiii. 2061. 
3 Fischer and Kuzel, Ann. Chem. Pharm. ccxxi. 266, 


AMIDOCINNAMIC ACIDS, 221 





Ethyl orthamidocinnamate, CjH,(NH,)C,H,.CO.OC,H,, is 
readily prepared by the reduction of the corresponding nitro- 
cinnamic ether with tin and hydrochloric acid and is precipi- 
tated by sodium acetate, after the removal of the tin by sul- 
phuretted hydrogen, in light yellow needles, which melt at 
77°—78° and readily dissolve in alcohol, forming a yellow solution, 
which has a strong yellowish-green fluorescence, Its hydro- 
chloride forms colourless needles and is partially dissociated 
when its solution is heated, the liquid being yellow while hot 
and becoming colourless again on cooling. 

_ Since the ether is quantitatively hydrolyzed by alcoholic potash, 
orthamidocinnamic acid can also be readily prepared from the 
ether of orthonitrocinnamic acid.? 

Ethyl orthamidocinnamic acid, C,H,(NH.C,H,)C, H, .CO,H. is 
formed when orthamidocinnamic pet and as ‘edida are 
heated with alcoholic potash. It is only slightly soluble in 
water, readily in alcohol, forming a yellowish solution with a 
green fluorescence, and separates from high-boiling petroleum- 
ether in fascicular groups of yellow needles, which melt at 
125°2 

Diethylorthamidocinnamie acid, C,H,N(C,H;),C,H,.CO,H, is 
formed along with the preceding compound and crystallizes 
from alcohol in light, citron-yellow plates, which melt at 124° 
and form a yellow solution in alcohol, which has a bluish-green 
fluorescence. 

Nitrosd-ortho-ethylamidocinnamic acid, C ,H,N(C,H;)N O)C,H,. 
CO,H, is formed by the action of sodium nitrite on a cooled 
solution of ethylamidocinnamic acid in dilute sulphuric acid 
and crystallizes from dilute alcohol in yellowish, lustrous plates, 
which melt with decomposition at 150°. 

a-Nitro-orthamidocimnamie acid, C,H,(NO,)(NH,)C,H,.CO,H. 
Two isomeric acids are formed when 1 part of orthamido- 
cinnamic acid is dissolved in 5 parts of sulphuric acid and 
a solution of 3 parts of saltpetre in 10 parts of sulphuric 
acid added, the temperature not being allowed to rise above 0°. 
If the solution be poured upon ice and diluted with a large 
amount of water, the @-compound separates out after some 
time. The a-compound, which is the chief product, crystallizes 
from the mother-liquor after the addition of caustic soda solu- 
tion until the reaction is only faintly acid. It forms light 


1 Friedlander and Weinberg, Ber, Deutsch. Chem. Ges. xv. 1422. 
2 Ibid. ; Fischer and Kuzel, Ann. Chem. Pharm. ecxxi. 267. 


299, AROMATIC COMPOUNDS. 


brownish-red needles, which melt at 240°, are only slightly 
soluble in water and dissolve readily in alcohol. © 

B-Nitro-orthamidocinnamic acid crystallizes in brownish- 
yellow needles, which melt at 254° and are almost insoluble 
in water. 

Metamidocinnamic acid is obtained in a similar manner to the 
ortho-acid. It crystallizes from hot water in long stellate or 
fan-shaped groups of light greenish-yellow needles, melting at 
180°—181°. It combines both with acids and bases. 

Paramidocinnamic acid crystallizes from hot water in fine, 
light yellow needles, grouped in spherical aggregates, which 
melt at 175°—176°. The reactions of this substance and its 
isomerides have been investigated by Tiemann and Opper- 
mann.” | 


1 Friedlander and Lazarus, Ann. Chem. Pharm. ccxxix. 241. - 
2 Ber. Deutsch. Chem. Ges. xiii. 2067. 


THE CARBOSTYRIL GROUP. 


2397 Carbostyril, C,H,NO, was prepared by Chiozza by heat- 
ing crude nitrocinnamic acid with ammonium sulphide,’ while 
Kihner obtained it from the same source by reduction with 
tin and hydrochloric acid.2, Morgan, who prepared it in the same 
way from pure nitrocinnamic acid, found that it is also formed 
when the ethyl ether of this acid is heated gently with ammonium 
sulphide.* It is therefore formed from orthamidocinnamic acid 
by the elimination of water: 


/ SH=CH.CO.OH CH—CH 
C,H, Bk GAs eo) euUh arene. 
\NH, \NH—CO 


The free amido-acid cannot however be directly converted into 
carbostyril, but shows a great tendency to form a resinous mass, 
and decomposes on heating. Carbostyril is however formed when 
acetylorthamidocinnamic acid is heated.‘ It is also formed, accord- 
ing to the researches of Tiemann and Oppermann, as a by- 
product in the preparation of orthamidocinnamic acid, and is 
readily obtained by heating an acid aqueous solution of the 
hydrochloride for some time.? In order to prepare carbostyril, 
ethyl orthonitrocinnamate is heated on the water-bath with 
alcoholic ammonium sulphide. The compound of ammonia with 
hydroxycarbostyril (see below) separates on cooling in flakes, 
which are filtered off. The filtrate is then evaporated and the 
residue extracted with a very dilute, hot solution of sodium 
carbonate. The carbostyril is then precipitated by passing 
carbon dioxide through the lquid, while hydroxycarbostyril 


1 Ann. Chem. Pharm. 1xxxiii. 117. 2 Zeitschr. Chem. 1865, 2. 
3 Chem. News, xxxvi. 269. 

4 Baeyer and Jackson, Ber. Deutsch. Chem. Ges. xiii. 115. 

5 Ibid. xiii. 2069. 


224 AROMATIC COMPOUNDS. 


remains in solution and is finally separated by the addition of 
sulphuric acid.* 

Carbostyril may be even more readily prepared by heating 
ethyl orthamidocinnamate with hydrochloric acid in a sealed 
tube.2 It is scarcely soluble in cold, readily in hot water and 
alcohol, and crystallizes in large, lustrous prisms, which melt at 
199°—200° and sublime in needles at a higher temperature. 
Potassium permanganate oxidizes it in alkaline solution to isatin 
and oxalortho-amidobenzoic acid, which is formed according to 
the following equation : 


CH=CH. CO.0OH 
Cari |i ied 2 Reet 
6 Be 6 aN 
NH—CO NH—CO.CO.OH. 


Pseudo-isatin is then formed by loss of water and carbon dioxide 
and immediately passes into isatin. 

Carbostyril contains one atom of hydrogen which can be 
replaced by metals and alcohol radicals. Phosphorus penta- 
chloride converts it into monochloroquinoline, C,H,CIN (p. 168), 
which is reconverted into carbostyril by water at 120°. 

Methylearbostyril, Cy5xH,NO(CH,), is obtained by heating 
chloroquinoline with sodium methylate and methyl alcohol. 
It is an oily liquid, which smells like oranges and_ boils 
at 246°—247°, 

Ethylearbostyril, C>H,NO(C,H,), is formed when carbostyril 
is heated with ethyl iodide and alcoholic potash, as well as when 
chloroquinoline is heated with alcoholic potash, and may also be 
obtained by heating ethyl orthamidocinnamate with a concen- 
trated alcoholic solution of zine chloride.t It is an oily liquid, 
which has a sweetish, penetrating odour, boils with slight 
decomposition at 250° and solidifies in a freezing mixture to 
crystals, which melt below 0° It combines with acids to 
form deliquescent salts; it is very stable towards alkalis, but 
is reconverted into carbostyril by dilute hydrochloric acid 
at 120°. 

Phenylearbostyril, Cj5H,NO(C,H,), is obtained by heating a 
solution of chloroquinoline with sodium phenate and phenol ; 
it crystallizes from alcohol in lustrous plates, melting at 
68°—69°. 


1 Friedlander and Ostermaier, Ber. Deutsch. Chem. Ges. xiv. 1916. 
* Friedliinder and Weinberg, ibid. xv. 1421. 
3 Friedlander and Ostermaier, 2bid. xv. 332. 
4 Friedlinder and Weinberg, ibid. xv. 2013. 


THE CARBOSTYRIL GROUP. 225 





In view of the formation and decompositions of chloroqui- 
noline, carbostyril must be considered as hydroxyquinoline and 
its constitution expressed by the following tautomeric formule : 











Carbostyril. j Ilydroxyquinoline. 
HG GFt HC CH 
Ho? \ \cu Ho” \ \cH 
| 1 | 

I Of 
Le Ge aaa SNA ea 
HO NA HC N 


According to the first formula it is the lactam, according to the 
second the lactim, of orthamidocinnamic acid. 

a-Nitrocarbostyril, CyH,(NO,)NO, is formed when a-nitro- 
orthamidocinnamic acid is heated to 150° with hydrochloric 
acid, and crystallizes from alcohol in fine needles, which remain 
solid at 320°. 

—B-Nitrocarbostyril is obtained in a similar manner from the 
8-acid and is also formed, together with the ethyl ether of the 
a-acid, by the nitration of ethyl orthamidocinnamate. It is 
almost insoluble in alcohol, and crystallizes from hot, glacial 
acetic acid in thick, yellow needles, melting at 260°, forms a 
brick-red solution in caustic soda and is reprecipitated by 
carbon dioxide. 

y-Nitrocarbostyril is prepared by the action of a mixture of 
nitric and sulphuric acids on carbostyril. It crystallizes from 
acetic acid in long, white needles, which melt at 200° and form 
a yellow solution in caustic soda. 

y-Amidocarbostyril, CjH,(NH,)NO, is formed by the reduc- 
tion of the preceding compound with tin and hydrochloric acid. 
It crystallizes from glacial acetic acid in slightly soluble, yellow 
plates, which do not melt below 320°. 

2398 Cynurin, C,H,NO. Liebig, in 1853, discovered a new 
acid in the urime of the dog and named it cynurenic acid, in 
order to indicate its source, On heating, it yielded a sublimate, 
which differed from the original acid, and on dry distillation it 
gave an oily liquid, smelling like benzonitril. Two analyses 
gave numbers which led to the composition C,,H,,N,O,,? while 
Schmiedeberg and Schulten found that its formula is C,,H,,N,O,, 
and that it decomposes on heating into carbon dioxide and 


1 Friedlander and Lazarus, Ann. Chem. Pharm. ecxxix. 245. 
2 Ibid, Ixxxvi, 125 ; eviii. 354; exl, 143. 


226 AROMATIC COMPOUNDS. 


cynurin,' C,,H,,N,O,. This substance was recognized by 
Kretschy as a hydroxyquinoline and the cynurenic acid as 
hydroxyquinolinecarboxylic acid, C,H,NO(CO,H). According 
to him, it is formed in considerable quantity when a diet 
consisting exclusively of flesh is administered.” 

In order to extract it from dog’s urine, a considerable amount 
of this is treated with dilute hydrochloric acid (1 in 10) and 
precipitated with phosphotungstic acid, the precipitate bemg 
then decomposed by baryta.?® It is scarcely soluble in cold 
water; when it is set free from a hot solution in ammonia 
by the addition of acetic acid and the whole allowed to cool, it 
crystallizes in brilliant needles, contaming one molecule of water, 
which is lost at 140°—145°. On evaporation with hydrochloric 
acid and potassium chlorate, a reddish residue is left, which 
becomes brownish green and then emerald green when moistened 
with ammonia; the intensity of the colouration increases on 
exposure to the air.* 

Cynurenic acid melts at 253°—258° and decomposes into 
carbon dioxide and cynurin, which crystallizes from hot water on 
rapid cooling in needles containing three molecules of water, but 
on gradual cooling in anhydrous, lustrous, monosymmetric prisms 
or tablets, which have a bitter taste and a faint alkaline reaction. 
Its hydrochloride crystallizes in needles, which readily lose hydro- 
chloric acid. | 

Cynurin melts at 201°, sublimes very slowly when further 
heated and boils with decomposition at 300°, an oily liquid being 
formed. Phosphorus pentachloride converts 1t into monochloro- 
quinoline, which crystallizes well but is very unstable. When 
cynurin or cynurenic acid is heated with zinc dust in a current of 
hydrogen, it is reduced to quinoline, while potassium perman- 
ganate oxidizes them to oxalorthamidobenzoic acid.° 

Cynurin is therefore very similar to the isomeric carbostyril ; 
when orthamidobenzaldchyde is heated to 120° with malonic acid, 
car DOR Aare 9 acid, isomeric with cynurenic acid,is formed : 


CHO  CH,.CO.0H 
+ | = 
vetla NE, CO,H 
Che Cs CO.OH 
HK 
Agia os ONES 
1 Ann. Chem. Pharm. elxiv. 155. 2 Monatsh. Chem. ii. 57. 


3 Hofmeister, Ber. Deutsch. Chem. Ges. xiv. 688. 4 Jaffé, cbid. xvi. 1511. 
5 Kretschy, Monatsh. Chem. vy. 16. 


+ 2H,0. 





CYNURIN. 227 


This is very slightly soluble in water, but more readily in 
boiling alcohol, from which it crystallizes in broad needles or 
long-pointed prisms, which melt above 320°. 

2399 a-Hydroxycarbostyril, C,H_N O,, is formed, as stated above, 
in the preparation of carbostyril, which it resembles very closely. 
It melts at 190°5° and sublimes in fine needles at a higher 
temperature. It crystallizes from hot water, in which it is only 
slightly soluble, in nacreous plates, which like those of orthnitro- 
cinnamic acid become deep red on exposure to light. It is a 
strong monobasic acid and decomposes carbonates ; when its solu- 
tion is heated with a few drops of nitric acid, 1t becomes coloured 
deep red. It is reduced by zinc dust and hydrochloric acid to 
carbostyril and is oxidized by potassium permanganate to ortho- 
nitrobenzoic acid. 

Lithoxycarbostyriul, CsH,NO,(C,H;), is obtained by heating 
the potassium salt of oxycarbostyril with ethyl iodide. It erys- 
tallizes from a mixture of ether and petroleum-ether in splendid 
thick prisms, which melt at 73° and volatilize at a higher 
temperature without decomposition. It is a strong base (Fried- 
linder and Ostermaier). 

a-Hydroxycarbostyril is probably an isonitroso-compound : 





OH=CH 
CHS | 
Pie NN AS 00 
OH 


Its oxidation to orthonitrobenzoic acid is readily explained 
by this formula. 

8-Hydroxycarbostyril or a-B-Dihydroxyquinoline. When the 
a--dichloroquinoline, which is obtained from hydrocarbostyril 
(p. 168) is heated to 120° with dilute hydrochloric acid, B-chloro- 
carbostyriul, C,H,CIN, is formed; it resembles carbostyril and 
melts at 241°—242°. On fusion with potash it is converted into 
8-hydroxycarbostyril, which is a feeble base and is precipitated 
by water from its solution in hydrochloric acid in needles, which 
melt above 800° and sublime. It is simultaneously a weak 
monobasic acid of the following constitution : ? 


Ga OEE 


GH. , 
“N= C'6H 


1 Friedlander and Gohring, Ber. Deutsch. Chem. Gres. xvii. 459, 
2 Friedlander and Weinberg, ibid. xv. 2679. 


228 AROMATIC COMPOUNDS. 


y-Hydroxycarbostyril or a-y-Dihydroxyquinoline 1s formed 
when orthamidophenylpropiolic acid is heated with sulphuricacid : 


/S=0.00.00 0 
OM ay —— CHA | ; ot H,0 = 
\NH, NH—CO 
OH OH 
| | 
C—cH C—CH 
C,H 


Be seh oue pope 
NTO ON ae) OT 


It behaves in a very similar manner to the 8-compound and 
crystallizes in needles, which sublime above 320° without melting. 

y-Chlorocarbostyril, C,H,C1NO, is formed when the amido-acid 
is boiled with hydrochloric acid, and crystallizes from hot alcohol 
in silky needles, melting at 246°, which sublime at a higher 
temperature. On heating with phosphorus pentachloride, a-ry- 
dichloroquinoline, which melts at 67°, is formed. 

y-Bromocarbostyril, C,H,BrNO, is obtained by boiling amido- 
propiolic acid with hydrobromic acid and by treating ethylcar- 
bostyril with bromine vapour, an unstable addition-product being 
first formed, which readily decomposes with formation of ethyl- 
bromocarbostyril. The latter is then converted into y-bromo- 
carbostyril by heating to 120° with hydrochloric acid (Friedliinder 
and Weinberg). 

Its constitution is expressed by the following tautomeric 
formule. : 

CBr—CH CBr—CH 
Le C,H 

BA nado m\y—Con 


It crystallizes from alcohol in needles, which melt at 266°. 
The following remarkable relation exists between the three closely 
connected acids, orthamidohydrocmnamic acid, orthamidocin- 
namic acid, and orthamidopropiolic acid. The first changes 
immediately into its immer anhydride, the second can only be 
converted into an anhydride under certain conditions, while the 
anhydride of the third has not yet been obtained, since when the 
side-chains join to form a ring, this is invariably accompanied by 
the addition of water, hydrochloric acid, &c., to the triple-linked 
carbon atom (Baeyer). . 


1 Bacyer and Bloem, Ber. Deutsch. Chem. Gics. xv. 2147. 


QUINISATIC ACID. 229 


2400 Quinisatic acid, C,H,NO,. When a solution of y-hydroxy- 
carbostyril and sodium nitrite is poured into dilute sulphuric acid, 
a brick-red precipitate of nitroso-y-hydroxycarbostyril, C,5H,N.,0,, 
is formed, which crystallizes from alcohol in small orange-yellow 
prisms and is converted into B-y-dihydroxycarbostyril by treat- 
ment with stannous chloride and subsequent oxidation in the air. 
This substance, which crystallizes in long needles, is oxidized to 
quinisatic acid by ferric chloride. 

The constitution of these compounds is probably expressed by 
the following formule : 


Nitroso-y-hydroxycarbostyril. B-y-Dihydroxycarbostyril. 
OH 


| 
CO-CN.OH Jeon 

HC CHK | 
Na. Not 


Quinisatic Acid, 


CO.C0.CO.0OH 
nee 
6 ab ’ 
NH, 


C 


C 


Quinisatic acid is tolerably soluble in cold, very readily in hot 
water, from which it crystallizes in straw-yellow prisms. Its 
alkali salts are almost colourless and readily soluble ; the silver 
salt is a yellowish-green, very unstable precipitate. 

Quinisatin, C,xH,NO,, is formed when quinisatic acid is heated 
to 120°—125°, the crystals becoming red without undergoing any 
alteration in form, It forms a yellowish-red solution in absolute 
alcohol and is reconverted into quinisatic acid when covered with 
water or allowed to le in the air. 

The constitution of quinisatin is expressed by one of the 
following formule :1 


CO—cCOo 0-00 
CH | CH | 
ee SNH eee Nee Gl OE 


1 Baeyer and Homolka, Ber. Deutsch. Chem, Ges, xvi. 216. 


230 AROMATIC COMPOUNDS. 


HYDRAZINE DERIVATIVES OF CINNAMIC 
ACID.} 


2401 Orthohydrazinecinnamic acid, C,H,(N,H,)C,H,.CO,H. 
In order to prepare this substance, 10 parts of orthamidocin- 
namic acid are dissolved in 9 parts of concentrated hydrochloric 
acid and 70 parts of hot water, the solution allowed to cool 
until crystals begin to separate out and the calculated quantity of 
sodium nitrite added, the liquid being well stirred and kept cool. 
The hydrochloride of diazocinnamic acid separates out after a 
short time as a yellow, crystalline powder, which is converted by 
a solution of normal sodium sulphite into the sodium salt of 
diazosulphocinnamic acid. This is reduced by the action of zinc 
dust and hydrochloric acid to the hydrazine compound, which 
is converted by hydrochloric acid into the hydrochloride of 
orthohydrazinecinnamic acid : 


CH= CH.CO,H 
C + H,O + HCl = 


oH 
NH—NH.SO,Na 


CH—CH.CO.H 


C + SO,HNa. 


H 
*"\NH—NH,Cl 


If it be dissolved in water and sodium acetate added, the free 
hydrazine-acid is precipitated in yellowish crystals, which are 
only very shghtly soluble in hot water and decompose on 
re-crystallization or on the evaporation of their solution. Its 
solution in acetic acid bleaches litmus and indigo. It reduces 
Fehling’s solution and ammoniacal silver solution, and melts at 
171° with formation of acetic acid and indazol (p. 64). 

Orthohydrazinecinnamic anhydride, CjH,N,O. This compound, 
which is also called amidocarbostyril, is formed by boiling sodium 
hydrazinesulphocinnamate with dilute hydrochloric acid, and 
crystallizes from hot water in fine needles, which melt at 127°, 
sublime without decomposition and do not reduce Fehling’s 


1 Fischer and Kuzcl, Ann. Chem. Pharm. ecxxi. 261; Fischer and Tafel, <2b7d. 
eexxvii. 303. 


~ INDAZOLACETIC ACID. 231 


solution or silver solution. It is a feeble base, the hydrochloride 
of which crystallizes in prisms. When sodium nitrite is added 
to a faintly acid solution, carbostyril is precipitated, so that it 
must have the following constitution : 


Jahon St 
oH | 
6 PSs. 
N=— GO 
| 
NH, 


2402 Indazolacetic acid, C,;H,N,O,, is very readily obtained by 
agitating an alkaline solution of hydrazinecinnamic acid in the 
air until it no longer reduces Fehling’s solution : 


CH,.CO,H 
| 
CH—CH—CO,H an \ 
C,H Ore: GLH NH 15 Ke) 
6 *\NH—NH, oe 6 WY ts 2 


The indazolacetic acid separates out on the addition of hydro- 
chloric acid and crystallizes from hot water in fine needles, which 
are generally slightly yellow and decompose at 168°—170° into 
carbon dioxide 4nd methylindazol. 

The copper salt, (C,H,N,O,)Cu + 2H,0, is a characteristic 
compound. It separates on the addition of copper acetate to a 
solution of the acid in dilute acetic acid as a pale green, viscid 
precipitate, which is quite insoluble in hot water, but crystallizes 
from hot alcohol in fine needles, which, after drying in a vacuum, 
form an extremely light powder. 

Indazolacetic acid also combines with acids. 

Monobromindazolacetic acid, C,H,Br(CN,H)CH,.CO,H. In 
order to prepare this compound, indazolacetic acid is dissolved 
in dilute hydrochloric acid and an equal weight of bromine 
dissolved in water added. The precipitate is treated with 
animal charcoal and recrystallized first from glacial acetic acid 
and then from water. It is thus obtained in matted needles, 
which melt at 200° with a vigorous evolution of gas. 

Monobromindazolcarboxylic acid, C;H,;BrN,O,. Indazolacetic 
acid itself is completely destroyed by the usual oxidizing 
agents, while the monobromo-derivative is converted by a 

281 


232 - AROMATIC COMPOUNDS. 





solution of chromic acid in acetic acid into bromindazolcarboxylic 
acid : / £8, COH 

| O,H,Br i 
Oat 


NH +30 = 


C 
OJH,Br re NH + H,0 + CO, 

This is almost insoluble in water and dilute hydrochloric acid, 
and crystallizes from hot glacial acetic acid in matted needles, 
which are readily soluble in the alkalis and their carbonates. 
On heating with water to 200°, it decomposes into carbon dioxide 
and bromindazol. 

Ethylisindazolacetic acid, C,,H,,.N,O,. When nitro-ortho- 
ethylamidocinnamic acid is reduced with zine and acetic acid, 
the corresponding hydrazine acid, which rapidly oxidizes in the 
air, is formed : 


EH, CO,H 
CH—CH.CO,H DR 
O,H, On ee +H,0. 
\N—NH, \ndé 
| Nou, 
C,H, 


The ethylisindazolacetic acid thus obtained separates from hot 
water as an oil, which rapidly solidifies to fine plates, melting at 
131°. If these be dissolved in chloroform and the solution 
diluted with petroleum-spirit, aggregates of fine plates, melting 
at 126°, are obtained, which change into compact crystals, 
melting at 131°, when left in contact with the mother-liquor; it 
decomposes at 162° into carbon dioxide and ethylmethisindazol. 

Lthylbromisindazolacetic acid, C,,H,,BrN,0,, is formed by the 
action of bromine on an acetic acid solution of the preceding 
compound. It crystallizes from hot water in fan-shaped 
ageregates of needles. 

LEthylbromisindazolearboxylic acid, C,jJHyBrN,O,, is obtained 
by the oxidation of the preceding compound, the aldehyde 
being formed as an intermediate product : 


ae 9/0008 
\ 
CHBKC YN CHB ON 


\o,H, \o,H, 


ATROPIC ACID. 233 


The latter crystallizes from wood-spirit in long prisms, which 
melt at 88° and volatilize without decomposition. The acid 
forms characteristic, bent needles, which melt at about 210° and 
decompose when more strongly heated into carbon dioxide and 
ethylbromisindazol, 


ATROPIC ACID, OR a PHENYLACRYLIC ACID, 


2403 This compound was first prepared by Kraut, who treated 
atropine with baryta water! and was then obtained by Lossen 
by heating the same substance with hydrochloric acid,? the 
tropic acid, C,H,;.CH(CH,.OH)CO,H, which is the first product, 
decomposing into water and atropic acid. It is also formed 
when ethylatrolactic acid, C,H,.C(CH,)(OC,H,)CO,H, is boiled 
with hydrochloric acid? and when chlorohydratropic acid is 
heated with caustic soda.‘ 

In order to prepare it, 1 part of atropine is boiled with 
2 parts of barium hydroxide and 20 parts of water for 15 
hours, evaporated to some extent and filtered. Hydrochloric 
acid is then added to the hot filtrate and the whole allowed 
to cool. The greater portion of the atropic acid separates 
on cooling, the remainder being extracted with ether.’ It 
crystallizes from hot water in needles and from alcohol in 
monosymmetric tablets, which melt at 106°—107°, are volatile 
with steam and boil with decomposition at about 267°. It 
is oxidized by chromic acid to benzoic acid, while formic 
and phenylacetic acids are formed when it is fused with 
caustic potash. 

It is reduced by nascent hydrogen to hydratropic acid. 

It differs from the isomeric cinnamic acid in that it dissolves 
in 692 parts of water at 19° and is not precipitated from a 
neutral solution by manganese chloride. 


1 Ann. Chem. Pnarm. exxviil. 282. 

2 Ibid. exxxviii. 230. 

3 Ladenburg and Riigheimer, Ber. Deutsch. Chem. Gres, xiii. 2042. 
4 Spiegel, ibid. xiv. 237. : 

5 Fittig and Wurster, dunn. Chem. Pharm. cxcv. 147. 


234 AROMATIC COMPOUNDS. 


Caleium atropate, (Cj,H,0,)Ca + 5H,0, forms large, mono- 
symmetric crystals, which dissolve in 43 parts of water at 18° 
(Kraut.) 

Isatropic acid, C,,H,,O, Lossen discovered that isatropic 
acid is formed in addition to atropaic and tropaic acids when 
atropine is heated with hydrochloric acid.’ Fittig and Wurster 
then observed that this substance is always formed in small 
quantity when atropic acid is recrystallized from boiling water, 
more largely when the solution is boiled for some time or the 
acid heated alone,?and Fittig has finally shown that two isomeric 
acids are thus formed.® 

a-Isatropic acid is the chief product and is almost exclusively 
formed when atropic acid is gradually heated to 140°—160° for 
24—36 hours in a closed flask. After cooling, it is heated with 
a little acetic acid or alcohol, again allowed to cool, the coloured 
liquid poured off and the residue recrystallized from acetic 
acid. It forms small crystals united to crusts or warty masses, 
melts at 237°—237°5°, is only very slightly soluble in water 
and is almost insoluble in ether. When slowly distilled it 
decomposes almost completely into atronol, C,,H,,, carbon 
monoxide and carbon dioxide, while on rapid heating atronic 
acid, C,,H,,0,, is also formed, a portion of the a-acid passes over 
unchanged and a second portion is converted into the @-acid. 

It does not combine with bromine in the cold and is not 
altered by the action of water and sodium amalgam. 

B-Isatropic acid is formed in relatively large amount when 
the acid is ‘boiled with water, crystallizes from hot water in 
small, lustrous, quadratic tablets and separates from acetic acid 
either in thick, transparent, four-sided tablets, or in druses of 
apparently octahedral crystals, which contain a molecule of 
acetic acid, It melts at 206° and is converted at 220°—225° 
into the a-acid. 

These acids have identical chemical properties. On oxidation 
with chromic acid they yield carbon dioxide, acetic acid, ortho- 


benzoylbenzoic acid, C,H,.CO.C,H,.CO,H, and anthraquinone, 
Tens 

Os, C,H, These compounds and the other decom- 
\co” 


position products of the acids in question will be subsequently 
described, 


1 Ann. Chem. Pharm, cxxxviii, 237. 2 Thid. excv. 147. 
3 Ibid. cevi. 34. 4 Kraut, zbid, exlviii. 246. 


PHENYLHYDROXYACRYLIC ACIDS. 235 


The two isatropic acids appear to be physical isomerides and 
probably have the following constitution : 


CO,H 
One| 
pigeons) eu 


C,H 
EC ont, 


| 
CO,H 


PHENYLHYDROXYACRYLIC ACIDS. 


2404 The two isomeric acids which can exist according to 


theory : 
a B 
C,H,.CH—C(OH)CO,H Cro CKO CH. COL 


are unknown, since they are immediately converted into the 
isomeric phenylglycidic acid. Their derivatives have, however, 
been prepared. 

Phenoxycinnamic acid, C,H;.CH—C(OC,H,)CO,H, is formed, 
together with cinnamic acid, when sodium _ phenylglycolate 
(Pt. IIL. p. 111) is heated with benzaldehyde and _ acetic 
anhydride, and crystallizes from alcohol in prisms, which melt 
at 179°—180° 

a-Chlorocinnanie acid or Phenyl-a-chloracrylic acid, C,H,.CH= 
CCI.CO,H, is obtained, accompanied by the #-acid, by the 
action of alcoholic potash on phenyldichloropropionic acid. It is 
the chief product of the reaction and can readily be separated 
from the isomeric acid by means of its potassium salt, which is 
only slightly soluble in alcohol.? It is also formed when 
benzaldehyde is heated with acetic anhydride and sodium 
chloracetate 3 and by the action of phosphorus pentachloride on 
‘the ethyl ether of benzoylacetic acid, C,H,;.CO.CH, CO,H, the 
f-acid being probably first formed and then converted into the 
a-compound, exactly as in the case of the corresponding bromine 
compound.* 

1 Oclialoro, Gaz. Chim. Ital. x. 481. 
2 Jutz, Ber. Dewtsch. Chem. Gics. xv. 758. 


3 Plochl, ibid. xv. 1945. 
4 Perkin, Journ. Chem, Soc. 1885, i. 256. 


236 . AROMATIC COMPOUNDS. 





a-Chlorocinnamic acid crystallizes from petroleum-spirit in 
long, thin needles, which melt at 142° and are slightly soluble 
in cold, somewhat more readily in hot water. 

B-Chlorocinnamic acid or Phenyl-B-chloracrylie acid, C,H,.CC1 
—CH.CO,H, forms long plates, melting at 114". 

a-Bromocinnamic acid or Phenyl-a-bromacrylie acid, C,H,.CH 
—CBr.CO,H, was obtained by Glaser, together with the 6-acid, 
by the action of alcoholic potash on phenyldibromopropionic 
acid,! 8-phenylbromethylene being simultaneously formed.? 
When hydrochloric acid is added to the product, the a-acid is 
first precipitated, then a mixture of the isomerides and finally 
the B-acid, which is the chief product. a-Bromocinnamic acid 
crystallizes from hot water in long, four-sided needles, which 
melt at 130°—131° 

B-Bromocinnamic acid or Phenyl-B-bromacrylic acid,C,H,.CBr= 
CH.CO,H, is very readily soluble in boiling water and separates 
in large, six-sided tablets, which melt at 120° and are converted 
into the a-acid by distillation or by heating with hydriodic acid ; 
its ether also undergoes this change on distillation at the ordinary 
pressure and both the ethers are converted by phosphorus 
pentachloride into the same bromocinnamyl chloride, C,H,.C,HBr. 
COCI, which is an oily liquid and is decomposed by water with 
formation of the a-acid.‘ 

Michael and Brown have obtained a third bromocinnamie 
acid by the combination of hydrobromic acid with phenyl- 
propiolic acid, C,H;.C = C.CO,H, which crystallizes in long, 
flat needles or rhombic tablets, melts at 158°5° and is converted 
into benzoylacetic acid by being dissolved in sulphuric acid.> 
Erlenmeyer, on the other hand, found that the acid which is 
thus formed melts at 153°5° and yields phenyl] propiolic acid, to- 
gether with phenylacetylene and 8-bromostyrolene, on treatment 
with sodium carbonate solution. Concentrated sulphuric acid 
converts it into benzoylacetic acid and acetophenone, while it is 
decomposed into acetophenone and a little phenylacetaldehyde 
by the action of hot hydrobromic acid. When its solution in 
glacial acetic acid is saturated with hydrobromic acid, an 
isomeric acid, which melts at 159°—160°, is formed. It is 
probably identical with the compound obtained by Michael and 


1 Ann. Chem. Pharm. exlvii. 830. 

2 Barisch, Jowrn. Prakt. Chem. [2] xx. 178. 
3 Glaser ; Plochl; Barisch, loc. ct. 

4 Anschiitz and Selden, zb7d. xx. 1382. 

5 Ber. Deutsch. Chem. Ges. xix. 1378. 


BROMOCINNAMIC ACIDS. 237 





Brown and also yields acetophenone and a large amount of 
phenylacetaldehyde on heating with hydrobromic acid. 

- According to Erlenmeyer’s views, the acid of lower melting- 
point is a compound of two molecules of 8-bromocinnamice acid, 
while the other contains equal molecules of the a- and -acids.! 


C,H, ©,H, C,H, ©,H;, 
| 
CBr CBr CBr CH. 
| | | | 
CH CH COT. CBr 
O O 
HOC<9>COH HOC<)>COH 


Wislicenus, on the other hand, assumes that these four bromo- 
cinnamic acids have the same molecular weight and are derived 
from two geometrically isomeric cinnamic acids, which stand in 
the same relation to one another as fumaric to maleic acid 
(Pt. IT. p. 216). 

Only one of these is known, its constitution being probably 
that represented by Fig. 2, the other (Fig. 3) is still to be 
discovered : 


H CoH; C,H, H 


H C0.H H CO.H 
Fic. 2. Fic. 3. 


It also appears from these figures that each cf these acids can 
yield two monobrominated derivatives.” 

2405 Orthonitro-B-hydroxycinnamic acid, C,H,(NO,)C(OH) = 
CHCO,H, is obtained by the action of alcoholic potash on ortho- 
nitrophenylchlorolactic acid; it crystallizes from hot water in 
flat needles, which decompose on heating, with elimination of 
carbon dioxide and formation of a small amount of indigo.’ 


1 Ber. Deutsch. Chem. Ges. xix. 1936. 
2 Raéumliche Anordnung der Atome, 47. 
3 Baeyer, Ber. Deutsch. Chem. Ges, xiii, 2262. 


238 AROMATIC COMPOUNDS. 


Paranitro-8-hydroxycinnamic acid is formed, together with 
paranitrochlorostyrolene and paranitrophenylchlorolactic acid, by 
the action of hypochlorous acid on sodium paranitrocinnamate, 
and forms small crystals, which decompose on heating.* 

Paranitrophenylnitro-acrylic acid or a-4-Dinitrocinnamic acid, 
C,H,(NO,)CH = C(NO,)CO,H, is deposited in snow-white, 
glistening plates, when a solution of paranitrocinnamic and 
sulphuric acids is allowed to run into a mixture of nitric and 
sulphuric acids at a temperature of — 20°. It loses carbon 
dioxide even at 0° and decomposes quantitatively into this 
and w-4-dinitrostyrolene in aqueous solution (p. 35). 

Ethyl paranitrophenylnitro-acrylate, C,H,(NO,)C,H(NO,)CO, 
C,H,, is formed when ethyl paranitrocinnamate is brought into 
a cooled mixture of 2 parts of concentrated nitric acid with 
4 parts of sulphuric acid and the solution poured upon ice. 
It crystallizes from hot benzene in lustrous, white flakes, 
which melt at 109°—110° and are oxidized to paranitro- 
benzoic acid by chromic acid. When boiled for some time with 
water, it is decomposed into paranitrobenzaldehyde, alcohol, 
nitromethane and carbon dioxide : 


| SH=O(NO,)00.00,H, 


CAH. 2H,O = 
6 ‘no, + atl, 
yD 
CH + HOCH, + CH,NO, + 00, 
NO, 


A similar decomposition is caused by sulphuric acid, the nitro- 
methane being however in this case decomposed with formation 
of hydroxylamine, which combines with the nitrobenzaldehyde 
to form paranitrobenzaldoxime. 

If the ether be boiled with alcohol, a reaction takes place 
and ethyl paranitrophenylethoxynitropropionate, C,H,(NO,)CH 
(OC,H,)\CH(NO,)CO,.C,H,, is formed. It crystallizes in mono- 
symmetric prisms and melts at 52°. Similar compounds are 
formed by other alcohols.? 

Metanitrophenylnitro-acrylic acid or a-3-Dinitrocinnamic acid 
is even less stable than the para-compound and decomposes at 
once into carbon dioxide and a-3-dinitrostyrolene. Its ethyl 


1 Erlenmeyer, Ber. Deutsch. Chem. Ges. xiv. 1868. 
? Friedlander and Mihly, Ann. Chem. Pharm. ccxxix. 210. 


HYDROXY PHENYLACRYLALDEHYDE. 239 





ether is obtained by the action of a mixture of nitric and 
sulphuric acids on ethyl metanitrocinnamate; it crystallizes 
from ether in thick, lustrous, asymmetric tablets. It behaves 
towards ammonia and alcohols in a similar manner to the 
para-compound and decomposes on boiling with water into 
metanitrobenzaldehyde, alcohol, nitromethane and _ carbon 
dioxide,! 


HYDROXYPHENYLACRYLALDEHYDE, 

ou 

GE : 
CH—CH.CHO 


2406 Couwmaraldehyde, When an aqueous solution of acetalde- 
hyde is run into a faintly alkaline solution of helicin at 50°, 
glucocoumaraldehyde is formed : 


Jo tn9s Jo en9s 
CoH + CH,.CHO = CoH + H,0. 
CHO CH—CH.CHO 

This substance crystallizes in fine needles and is decomposed 
by emulsin into sugar and coumaraldehyde, which forms long, 
fine, aromatic smelling needles, melting at 133°, 

The glucocoumaraldehyde is converted by sodium amalgam 
and water into the corresponding alcohol, which also crystallizes 
in needles and yields cowmaralcohol, C,H,(OH)C,H,.CH,.0OH, 
on treatment with emulsin. This substance is an oily liquid, 
which is coloured red by concentrated sulphuric acid.” 

Tiemann and Kees endeavoured to prepare coumaraldehyde by 
the condensation of salicylaldehyde and acetaldehyde, but were 
unsuccessful. The reaction succeeds however with the nitro- 
salicylaldehydes, if they be brought into contact with acetalde- 
hyde in alkaline solution? 

a-Nitrocoumaraldehyde, C,H,(NO,)(OH)C,H,0(5:2:1), is 
tolerably soluble in alcohol and almost insoluble in water, from 
which it crystallizes in fascicular groups of yellow needles, which 
melt with decomposition at 200°. 


1 Friedlinder and Lazarus, Ann. Chem. Pharm. cexxix. 233. 
2 Kees and Tiemann, Ber. Deutsch. Chem. Ges. xviii. 1955. 
3 Miller and Kinkelin, 7déd. xx. 1931. 


240 AROMATIC COMPOUNDS. — 





B-Nitrocoumaraldehyde (3 :2:1) crystallizes from dilute acetic 
acid in lustrous, golden-yellow needles and dissolves freely in 
hot water to form a deep orange-coloured solution, which colours 
the skin brick-red ; it separates on cooling in long, fine needles. 

Both these aldehydes reduce ammoniacal silver solution and 
form phenylhydrazones. 


HYDROXYPHENYLACRYLIC ACIDS, 
OH 


CHC 
CH—CH.CO,H 


2407 Cowmaric acid. This acid occurs associated with coumarin, 
which is its anhydride, in common melilot and faham leaves. 
Delalande and Bleibtreu obtained it by evaporating coumarin 
with caustic potash, and Fischer and Kuzel have prepared it 
from orthamidocinnamic acid by means of the diazo-reaction.? 
It is best obtained by dissolving 3°5 grm. of sodium in © 
60—70 cb. cm. of alcohol, adding 10 grm. of coumarin and heat- 
ing for one or two hours. Water is then added, the alcohol boiled 
off and hydrochloric acid added. The precipitate is dissolved in a 
cold solution of sodium carbonate, the small quantity of coumarin 
which remains undissolved is removed by ether and the coumaric 
acid again precipitated with hydrochloric acid and finally puri- 
fied by recrystallization from hot water. It crystallizes in 
long needles, which melt at 207°—208°,* are slightly soluble in 
cold, more readily in boiling water and readily in alcohol. It 
may be sublimed if carefully heated, but decomposes on 
distillation with formation of phenol and other substances. 
On fusion with potash it is decomposed into salicylic and 
acetic acid. 

Its solutions in ammonia and the alkalis show a characteristic 
green fluorescence. 

The coumarates. 'The metallic salts have been investigated by 
Zwenger. Its ethers, &c., will be described after coumarine. 

Acetyleowmarie acid, C,H,(OQCOCH,)C,H,.CO,H, is formed 
when salicylaldehyde is heated with acetic anhydride and sodium 
acetate, and crystallizes in needles, melting at 146°.4 

1 Zwenger, Ann. Chem. Pharm. Suppl. viii. 30. 2 Ibid. coxxi. 272. 


3 Fittig, ibid. ecxxvi. 351. 
* Tiemann and Herzfeld, Ber. Deutsch. Chem. Ges. x. 284. 


COUMARIN. ~ ° 241 


Coumarin, C,H,O,. Vogel, in 1820, stated that tonka beans, 
the seeds of Dipterix odorata, a tree which is indigenous in 
Cayenne, and is called cowmarow by the natives, contained 
benzoic acid and that he was led by the similarity of the smell 
of the tonka beans to that of common melilot (MJelilotus 
officinalis) to discover the presence of this acid in the latter 
and in woodruff (Asperula odorata). Guibort however showed 
that the crystalline constituent of tonka beans, is a distinct 
substance, which he named coumarin.? Boullay and Boutron- 
Challard confirmed this view,? and Guillemette pointed out 
that melilot contains the same compound, which was proved 
by Kossmann°® and by Bleibtreu® to be also present in woodruff. 
The latter chemist also found coumarin in the sweet-scented 
vernal grass (Anthoxanthum odoratum). In addition to these, 
it occurs in blue melilot (Melilotus cwruleus), which is employed 
for the preparation of herb-cheese, and in Melilotus vulgaris,’ 
as well as in Orchis fusca* and in the pleasant-smelling leaves 
of Angrecum fragrans, an orchid which is used in Réunion as 
tea, under the name of Faham.® According to Rother, the husks 
of Myroxylon pareire, the Peru balsam-tree (Pt. IV. 20), contain 
2 per cent. of coumarin.” 

Perkin has prepared it synthetically by heating sodium sali- 
cylaldehyde with acetic anhydride," and has also obtained it 
even more simply by boiling the aldehyde with the anhydride 
and sodium acetate.!*7 Acetylcoumaric acid is first formed and is 
then decomposed on heating into acetic acid and coumarin: # 


0.C0.CH, pecconsel 
: aeCry | + HO.CO.CH,. 
\CH=CH.CO.OH \cH—CH 


It is also formed in small quantities when malic acid is heated 
with phenol and sulphuric acid : 


CO.0H ,, .00.0F. ae Orar 
C.H,.OH + | Lp Renin | +43H,0+C0. 
CH(OH)—CH, JOYS bees Call 
} Gilbert's Ann. |xi. 161. 2 Drogues Simples. 


3 Berzelius, Juhresb. vii. 237; see also Delalande, Ann. Chem. Pharm, xlv. 
332 ; Wohler, zbid. xevili. 66. 

4 Ibid. xiv. 324. 5 Ibid. lii, 387. 6 Tbid. lix. 177. 

7 Reinsch, Jahresb. Chem. 1867, 439. 8 Bley, Pharm. Centralb. 1858, 827. 

® Gobley, "Jowrn. Prakt, Chem. 1. 286. ™ Year-book Pharm. 1885, 168. 

11 Chem. Soc. Journ. xxi. 53. 12 Ber. Deutsch. Chem. Ges. viii. 1599. 

13 Thiemer and Herzfeld, Joc. cit. 144 vy, Pechmann, zbid. xvii. 929, 


242 AROMATIC COMPOUNDS. 


Coumaric acid dissolves slowly in hydrobromic acid saturated 
at 0° and is thus converted into coumarin, which is precipitated 
by the addition of water after the solution has stood for some 
time (Fittig). 

Coumarin is scarcely soluble in cold water and crystallizes 
from boiling water in small, rhombic plates, while it separates 
from ethereal solution in larger rhombic crystals, melting at 67°. 
According to Perkin, it boils at 290°—290°5° and its vapour 
has a powerful action on the brain (Delalande). Bleibtreu 
was unable to determine what alteration it undergoes in the 
animal organism, since larger doses have a narcotic action and 
experiments to decide the question cannot on this account be 
carried out. It, like coumaric acid, is converted into hydro- 
coumaric acid by action of sodium amalgam and water. 

Coumarin is employed in perfumery, and for the manufacture of 
essence of woodruff. Bleibtreu says on this point: “The much- 
prized bouquet which distinguishes the May wine is nothing 
more than the aroma of this substance, and a purely scientific 
‘Maitrank, prepared with coumarin, was loudly approved of by 
a number of students in Bonn.” Rembertus Dodonezus, the 
celebrated botanist and physician of Maximilian II., mentions 
the custom of scenting wine with woodruff “to make the heart 
glad and the liver sound.” 

When one molecule of coumarin is boiled with two molecules 
of caustic soda, a solution is formed, which dries over sul- 
phuric acid to a yellow, gummy mass, which is converted at 
100° into a crystalline substance of the empirical formula 
C,H,O,(NaOH),. Acids precipitate coumarin from this sub- 
stance. When itis heated to 150°, the compound C,H,O,(Na,O) 
is formed, which is not a basic sodium coumarate, since it is 
decomposed by acids with formation of a brown, plastic mass. 
Caustic potash forms a similar compound, C,H,O,(KOH),, as 
does also baryta, the substance in this case being an amorphous 
deliquescent body of the formula C,H,OBa(OH),. Silver nitrate 
added to a solution of sodium coumarin, precipitates the silver 
compound C,H,O,(Ag,O), as a canary-yellow mass, which is 
reconverted on heating, or by the action of nitric acid, into 
coumarin.+ 

If coumarin be dissolved in concentrated hydrobromic acid, the 
solution cooled to 0° anda current of hydrobromic acid passed 


1 Williamson, Jowrn. Chem. Soc. 1875, 850 ; see also Ebert, Ann. Chem. Pharm. 
cexvi. 139. 


METHYLCOUMARINIC ACID, 243 





through it, crystals separate out, which redissolve at the ordinary 
temperature. After standing for some time however, lustrous 
transparent crystals appear, which decompose when removed 
from the liquid with evolution of hydrobromic acid and fall to 
a powder of coumarin.! 

2408 Methylcowmarinic acid, or a-Methyleowmarie acid, C,H, 
(OCH,)C,H,.CO,H, was obtained by Perkin by heating sodium 
coumarin with methyl iodide? and Ebert prepared it by heating 
a solution of equal molecules of coumarin, methyl iodide and 
sodium in methyl alcohol for several hours on the water-bath. 
It is readily soluble in alcohol and crystallizes in monosym- 
metric prisms or tablets melting at 88°—89°. 

Dimethyl coumarinate, C,H ,(OCH,)CH,.CO,.CH,, was prepared 
by Perkin by employing an excess of methyl iodide. It is an 
oily liquid, which boils at 275°—276°. 

B-Methylcoumarie acid was obtained by Perkin by heating 
methylsalicylaldehyde with acetic anhydride and sodium acetate, 
while Ebert prepared it by heating a solution of one molecule 
of coumaric acid, one molecule of sodium and two molecules of 
methyl iodide in methyl alcohol and hydrolysing the dimethy] 
ether which is thus formed. Perkin also found that it is formed 
when the a-acid is heated to its boiling-point, or when its 
concentrated alcoholic soluticn is exposed to sunlight, the 
B-acid commencing to crystallize out. The @-compound is also 
formed when sunlight is concentrated on the fused q-acid. 
This alteration is only brought about by the violet and ultra- 
violet rays. 

8-Methylcoumaric acid crystallizes in small, monosymmetric 
prisms, which melt at 182°—183° and are tolerably soluble in 
alcohol. 

B-Dimethyl coumarate is also formed when dimethyl coum- 
arinate is heated, and is a strongly refractive, thick liquid 
boiling at 293°, the vapour of which has the sp. gr. 6°95—6'78.4 

8-Methyleoumaramide, C,H,(OCH,)C,H,.CO.N H,, is obtained 
by treating the a- or 8-acid with phosphorus chloride and the 
resulting compound with ammonia, It crystallizes from alcohol 
in needles, which melt at 191°—192° (Perkin). 

Eithylcoumarinie acid or a-Kthyleoumarie acid, C,H,(OC,H,) 
C,H,.CO,H, has also been investigated by Perkin and by 


1 Fittig, Ann. Chem. Pharm. cexxvi. 347. 

2 Journ. Chem. Soc. 1877, 1. 414 ; ibid. 1881, 409. 
3 Ann. Chem. Pharm. cexvi. 160. 

4 Ebert, ibid. ecxxvi. 353. 


244 AROMATIC COMPOUNDS. 





Ebert.+ It is only slightly soluble in hot water, from which it 
crystallizes in white plates, while it separates from dilute alcohol 
in strongly refractive tablets, melting at 103°—104". 

Caleium ethyleoumarinate, (C,,H,,03),>Ca + 2H,0, crystallizes 
from hot water in radiating groups of lustrous needles. 

Ethyl ethylcoumarinate, C,H,(OC,H,;)C,H,.CO, C,H,,is a liquid, 
which boils at 290°—291°. 

8-Ethyleoumarie acid has been obtained by Perkin from 
ethylsalicylaldehyde and by Ebert from coumaric acid. It is 
also formed when the a-acid is heated and crystallizes from hot 
water in fine, lustrous needles and from alcohol in small prisms, 
melting at 135°. 

Calcium ethylcoumarate, (C,,H,,0,),Ca + 2H,0, crystallizes in 
large, hard needles and is much less soluble than ethyl 
cumarinate. 

Lithyl ethyleumarate is an oily liquid, which boils at 302°—304". 

The cause of the relations between the substituted coumarinic 
and coumaric acids is probably to be sought for in geometrical 
isomerism (p. 237). The chemical properties of both are 
identical; thus the two ethylated acids yield ethylsalicylaldehyde 
on oxidation and are reduced to ethylmelilotic acid by sodium 
amalgam and water (p. 173). If solutions of ethylcoumarinic 
acid and bromine in carbon disulphide be mixed, ethoxyphenyl- 
dibromopropionie acid, C,H,(OC,H,) CHBr.CHBr.CO,H, is formed 
in small crystals, which melt with decomposition at 155°. The 
same acid is also obtained from ethylcoumaric acid, which however 
combines much more slowly with bromine. The methylated 
acids behave in a precisely similar manner. The brominated 
compounds are converted by alcoholic potash into substituted 
phenylbromacrylic acids. 

Coumarin-melilotic acid, C,,H,,O;. According to Zwenger and 
Bodenberger, melilot does not contain free coumarin but this 
compound. It crystallizes in tablets, which are scarcely soluble 
in water but dissolve readily in alcohol and ether melts at 128° 
and is resolved into its components by ammonia.? Its constitution 
can be expressed by the following formula :® 


: )/ Hy CHy—CH,, CO, H 
\CO.CH=CH.C,H,.0H 


1 Ann. Chem. Pharm. cexxvi. 189. 
2 Ann. Chem. Pharm: exxvi. 257. 
3 Schiff, Ber. Deutsch. Chem. Ges. v. 665. 


THIOCOUMARIN. 245 


CH—CH 
K | ,1s formed when coumarin is 

O—--CS 
heated with phosphorus pentasulphide, and crystallizes from 
alcohol in long, golden-yellow needles, which melt at 101°, sub- 
lime when more strongly heated and do not possess a character- 
istic odour. It is reconverted into coumarin by heating with 
caustic potash. . 


Thiocoumarin, C,H. 


CH—CH 
Coumaroxime, CoH | , is obtained by the action of 
O—--C—N.OH 


hydroxylamine on an alcoholic solution of thiocoumarin, while 
coumarin itself does not react with hydroxylamin, It crystallizes 
from boiling water in long, white needles, which melt at 131° and 
are decomposed by heating with hydrochloric acid into coumarin 
and hydroxylamine. When it is heated with sodium ethylate 
and ethyl iodide, cowmaroxime ethyl ether, C,H,.C,H,O(NOC,H,), 
is formed ; it crystallizes from alcohol in plates, which melt at 
50°. If coumaroxime be treated with sodium amalgam and 
water, it is converted into hydrocowmaroxime, C,H,.C,H,O(NOH), 
which is readily soluble in water and alcohol and is decomposed 
into hydroxylamine and melilotic anhydride by heating with 
hydrochloric acid : 


CH: —CH, CH,—CH, 
C,H | Om AC HG | 4+ H,N.OH. 
6 oN 2 6 ~\ 2 
0—_C=N.OH ‘sof 
Gs fee Oa 


Coumarinphenylhydrazone, CHC | 
O—--C—N — NHOC,H,, is 

formed when thiocoumarin and phenylhydrazine are heated 
together in alcoholic solution, and crystallizes from alcohol in 
long, golden-yellow needles, melting at 143°—144°.1 

2409 Substitution products of cowmarin. When chlorine is 
passed into a solution of coumarin in chloroform, the dichloride, 
C,H,C1,0,, is formed as a thick, syrupy liquid, which is decom- 
posed by heat, or by the action of alcoholic potash, into the 
following compound. | 

a-Chlorocoumarin, C,H,.C,HCI1O,,is also formed when coumarin 
is heated to 200° with phosphorus pentachloride, and crystallizes 
from alcohol in long needles, which melt at 122°—123°? 


1 Tiemann, Ber. Deutsch. Chem. Ges. xix 1661. 
2 Perkin, Zeitschr. Chem. 1871, 178. 


246 AROMATIC COMPOUNDS. 


B-Chlorocowmarin, C,H .Cl.C;H,0,, is obtained by heating the 
sodium compound of chlorosalicylaldehyde with acetic anhydride 
and is a crystalline substance, melting at 162°4 

a-Bromocoumarin, C,H,.C,HBrO,. Coumarin combines with 
bromine to form the dibromide, C,H,.C,H,Br,O,, which crystal- 
lizes from alcohol in oblique prisms and from carbon disulphide 
in large prisms, melting at 105°. It is converted by alcoholic 
potash into bromocumarin, which forms prisms melting at 110°. 

B-Bromocoumarin, C,H,Br.C,H,O, has been prepared from 
bromosalicylaldehyde by Perkin. It is also formed, together 
with free coumarin and a-dibromocoumarin, when coumarin di- 
bromide is heated ; this last substance decomposes into coumarin 
and bromine, which then exerts a substituting action? 
8-Bromocoumarin crystallizes from alcohol in flat prisms, melting 
at 160°. 

a-Dibromocoumarin, C,H,Br.C,HBrO,, was obtained by Perkin 
by heating coumarin with bromine containing iodine ;* it crystal- 
lizes from boiling alcohol in small needles, which melt at 179° 
(Fittig). 

B-Dibromocoumarin, C,H,Br,.C,H,O,, was prepared by Perkin 
from dibromosalicylaldehyde. It is also formed when a solution 
of coumaric acid and bromine in carbon disulphide is allowed to 
stand. An addition product is formed and decomposes in the 
air into hydrobromic acid and dibromocumarin (Fittig). The 
latter crystallizes from alcohol in small, lustrous needles, melting 
at 177°. 

Nitrocoumarin, C,H;(NO,)O,, 1s formed by dissolving coumarin 
in fuming nitric acid, and by heating a-nitrosalicylaldehyde with 
sodium acetate. It crystallizes in fine needles, which melt at 
183° and form a deep-yellow solution in alkalis (Delalande, 
Bleibtreu). 

Amidocoumarin, C,H,(NH,)O,, is obtained by reducing nitro- 
coumarin with iron filings and acetic acid, and crystallizes in long , 
needles, melting at 168°—170°° 

Coumarilic acid, CyH,O,, has been prepared by Perkin by 
heating a-chlorocoumarin and a-bromocoumarin with alcoholic 
potash. It is best obtained by bringing coumarin dibromide 


1 Biisecke, Ann. Chem. Pharm. cliv. 85. 

2 Fittig and Ebert, zbid. ecxvi. 163. 

3 Fittig, Ann. Chem. Pharm. ccexxvi. 347. 

4 Perkin, ibid. clvii. 117. 

> Taege, Ber. Deutsch. Chem. Ges. xx. 2109. 

° Frapolli and Chiozza, Ann. Chem. Pharm. xev. 258. 


COUMARON. 247 





into hot alcoholic potash and then heating for a short time. 
It crystallizes from hot dilute alcohol in needles, melting at 
190°—191° and boils almost without decomposition at 310°— 
315°. It does not combine with bromine or hydrobromic acid 
and is decomposed into acetic and salicylic acids by fusion with 
potash. It is a monobasic acid and forms crystalline salts. 

Hydrocoumarilie acid, CyH,O3, is formed by the action of 
sodium amalgam and water on coumarilic acid, and is more 
readily soluble in water than the latter, crystallizing in nacreous 
plates, which melt at 116°5°. It boils with partial decom- 
position at 298°5°—300'5°, a small quantity of phenol being 
formed. Its salts crystallize well; the ethyl ether only dissolves 
slowly in caustic soda and is simultaneously saponified. 

Cowmaron, C,H,O,1is obtained by the distillation of coumarilic 
acid with lime, and by heating aldehydophenoxyacetic acid (Pt. IV. 
p. 289), with acetic anhydride and sodium acetate.2 It is an 
oily liquid, which boils at 168°5°—169°5°, is insoluble in alkalis and 
combines with bromine to form cowmaron dibromide, C,H,OBr,, 
which crystallizes from carbon disulphide in large, colourless 
prisms, melting at 86°. This substance is converted by the 
action of hot alcoholic potash into bromocoumaron, C,H,BrO, 
which crystallizes from dilute alcohol in needles, melting at 36°, 
volatilizes at the ordinary temperature and has a strong odour.? 

The following formulz express the most probable constitution, 
of these substances : 


Kan D ie acid. Coumaron. 
O 
CH, Cum S0:GOlH CH, CH 
6 *\cHZ 2 6 *\cHZ 
Hydrocoumarilic acid. 
easter © DN elskolansa 
6 DS 6irk ra 2 


The formation of coumaron from aldehydophenoxyacetic acid 
would then take place as follows: 


O—CH,,.CO,H 


SON 
C CH + H,O + CO, 


H Ee ee 
CHO ONTOS ca 


1 Fittig and Ebert, Ann. Chem. Pharm. ccxvi. 162. 
2 Rossing, Ber. Deutsch. Chem. Ges. xvii. 3000. 
3 Ebert, Ann. Chem. Pharm, cexxvi. 354, 


282 


248 AROMATIC COMPOUNDS. 





2410 Paracowmarie acid, C,H,.C,H,.CO,H. This compound 
was obtained by Hlasiwetz by boiling aloes with dilute sul- 
phuric acid, a yield of 1—1‘5 per cent. being given. It may 
be synthetically prepared by heating parahydroxybenzaldehyde 
with anhydrous sodium acetate and acetic anhydride to 175° in 
a sealed tube.2 It crystallizes from hot water in needles, melting 
at 206° (Tiemann and Herzfeld); its alcoholic solution is 
coloured dark golden-brown by ferric chloride. On fusion with 
caustic soda or potash, it is decomposed into parahydroxybenzoic 
acid and acetic acid. It is reduced to hydroparacoumaric acid 
by nascent hydrogen. 

Methylparacoumarie acid, C,H,(0CH,;)C,H,.CO,H, has been 
prepared by Perkin by heating anisaldehyde with acetic anhy- 
dride and sodium acetate, the method described under para- 
coumaric acid being followed (Higel). It crystallizes from 
alcoho] in faintly yellow needles, melting at 171°* It is also 
formed when sodium phenylglycolate is heated with anisaldehyde 
and acetic anhydride, methylphenoxyparacoumaric acid, (CH,O) 
C,H,.CH—C.(OC,H,;)CO,H, being simultaneously obtained ; the 
latter crystallizes from alcohol in rectangular tablets, melting 
at 200°.° 

Methylparacoumaryl chloride, C,H,(OCH,)C,H,.COCI, is a 
crystalline mass, which melts at 50° and is converted by 
ammonia into the amide, C,H,(OCH,)C,H,.CONH,, which 
separates from alcohol in scales, melting at 186°. 

Methyl methylparacoumarate, C,H,(OCH,)C,H,.CO,.CH,, is 
formed by the action of the chloride on methyl alcohol, crystal- 
lizes in large tablets, melts at 89° and boils at 303.° 

Ethyl methylparacoumarate, C,H,(OCH,)C,H,.CO,C,H,, occurs 
in the root of Hedychim spicatum, a plant related to the ginger, 
which is used in India as a perfume under the name of Kafur- 
kachri. A pleasant smelling oil and the above acid are ex- 
tracted by petroleum-spirit, the latter crystallizing in tablets, 
which melt at 49° and are decomposed by caustic potash into 
alcohol and methylparacoumaric acid.’ 

Acetylparacoumaric, C,H,(0O.COCH,)C,H,.CO,H, is formed 
when the sodium compound of parahydroxybenzaldehyde is 
heated with acetic anhydride and sodium acetate. It crystal- 

1 Ann. Chem. Pharm. exxxvi. 81 ; Eigel, Ber, Deutsch. Chem. Gles. xx. 2527. 

2 Tiemann and Herzfeld, ibid. x. 65; Kigel, doc, cit. 

3 Barth and Senhofer, zbid. xii. 1259. 4 Journ. Chem. Soc. 1877, i. 408. 


° Valentini, Gaz. Chim. Ital. xiv. 147. 6 Perkin, zbid. 1881, i. 439. 
7 Thresh, Pharm. Journ. Trans, [8] xv. 361. 


NARINGIN. 249 





lizes from hot water in fine, matted needles, which melt at about 
195°, but commence to sublime at a lower temperature. On 
heating with caustic potash it decomposes into acetic and 
paracoumaric acids. 

Naringin, C,,H,,0,, + 4,0, was discovered by De Vry in the 
flowers and almost all the parts of Citrus decwmana, and was 
mistaken by him for hesperidin (p. 251). Its name is derived 
from naringt (Sanscrit : orange). It has a bitter taste, is slightly 
soluble in cold, almost in every proportion in hot water and crystal- 
lizes in colourless, microscopic prisms, which lose water on heating 
and melt at 170°—171°. It forms a yellowish-red solution in 
alkalis and is reprecipitated by carbon dioxide, On heating with 
dilute sulphuric acid, it is decomposed into grape sugar, iso- 
dulcite and naringenin, C,,H,,0,;, which is insoluble in water 
and crystallizes from dilute alcohol in lustrous, tasteless needles, 
which dissolve readily in caustic potash and are decomposed 
when this solution is heated into phloroglucinol and paracoumaric 
acid.” Its constitution is therefore probably expressed by the 
following formula : 


HO.C,H,.CH=CH.CO.00,H,(OH),. 


Meantinee ero aS eee bs ACIDS, 


Last 
Care 
ie CO,H. 


2411 Caffeic acid (1:2:4). <A characteristic compound which 
is called caffeetannic acid, C,;H,,O, and forms a gummy mass, 
is contained in coffee beans ° and the cainca-root (Chiococca race- 
mosa).* On boiling with caustic potash, it decomposes into a 
sugar-like substance, C,H,,O,, and caffeic acid,’ which has also 
been prepared synthetically from protocatechualdehyde and 
acetic anhydride. 


1 Tiemann and Herzfeld, Pharm. Jowrn. Trans. [3] xv. 361. 

2 Will, Ber. Deutsch. Chem. Ges. xviii. 1811 ; xx. 294 and 1186. 

3 Pfaff, Schweiger’s Jowrn. lxii. 31; Rochleder, Ann. Chem. Pharm. lix. 300, 
Ixvi. 35. 

4 Rochleder and Hlasiwetz, Jahresber. ct 1850, 387. 

5 Hlasiwetz, dann. Chem. Pharm, cxlii. 2 


250 AROMATIC COMPOUNDS. 


In order to prepare it, 50 grms. of commercial coffee extract 
(Extract. coffee alc.), prepared by means of alcohol, are boiled 
with 100 grms. of water and 50 grms. of caustic potash for one 
hour, diluted with 200 grms. of water, acidified with sulphuric 
acid and repeatedly extracted with ether. The acid left after 
the evaporation of the ether is boiled up with animal charcoal 
and crystallized from water. The yield amounts to 6—7 grms.* 

Caffeic acid crystallizes in small, straw-yellow, lustrous prisms 
or plates and its aqueous solution is coloured grass-green by 
ferric chloride; the addition of sodium carbonate converts the 
colour into blue and finally imto reddish-violet. The acid is 
reduced to hydrocaffeic acid by sodium amalgam and water ; on 
distillation with potash it yields protocatechuic acid, while 
pyro-catechol is formed on dry distillation. 

Metamethyleaffeic acid, C,H,(OH)(OCH,)C,H,.CO,H(1 : 2: 4), 
was discovered by Barth and Hlasiwetz in Asa fetida, the resin 
of various species of Ferula or Narthesium and is called ferulaic 
acid.2 Tiemann and Nagai then prepared it synthetically from 
vanillin. It crystallizes in four-sided, rhombic needles, which melt 
at_ 168°—169° and are scarcely soluble in water, but dissolve 
more readily in boiling water and readily in alcohol. It is 
reduced to hydroferulic acid by sodium amalgam and water. 

Ferulaldehyde, C,H,(OH)(OCH,)C,H,.CHO. When gluco- 
vanillin (Pt. IV. p. 847) is acted upon by acetaldehyde and caustic 
soda, glucoferulaldehyde, C,H,(OC,H,,0,;)(OCH,)C,H,.CHO + 
2H,0, is formed, which crystallizes from hot water in light yellow 
needles, melting at 200°—202°. Its aqueous solution is laevo- 
rotatory, and colours a solution of fuchsin-sulphurous acid red. 
Emulsin resolves it into dextrose and ferulaldehyde, which is 
readily soluble in alcohol and benzene and is precipitated by 
petroleum-spirit from solution in the latter in light yellow 
needles, which melt at 84° and have a faint aromatic odour. Its 
solution is coloured bluish-green by ferric chloride, vanillin being 
formed if the mixture be heated.® 

Paramethyleaffeic acid, (2: 1:4), was prepared by Tiemann 
and Nagai by heating caffeic acid with methyl iodide, caustic 
potash and wood-spirit, and was called isoferulic acid Tiemann 
and Will then discovered that it is identical with hesperetic acid, 
a decomposition product of hesperidin.® It crystallizes in needles, 


* Ann. Chem. Pharm. exlii. 357. * Ibid. cxxxvili. 64. 
3 Tiemann, Ber. Deutsch. Chem. Ges. xviii. 3482. 4 Ibid. xi. 646. 
® Hoffmann, ibid. ix. 685 ; x. 686 ; Tiemann and Will, ibid. xiv. 946. 


HESPERETIN. 251 


which are slightly soluble in cold, more readily in hot water and 
alcohol and melt at 228°; it decomposes into carbon dioxide 
and hesperetol when its calcium salt is distilled (p. 32). 
Its alkali salts are colourless, while those of ferulaic acid have a 
yellowish colour. 


Melting-point. 
Dimethylcaffeic acid, C,H,(OCH,),C,H,.CO,H 
Wistrovs Ncedlos 61.4 Wa <n Gendt rn lag i) - 180°—181° 
Methyldemethyleaffeate, C,H,(OCH,),C,H,. 
CO. Gia. ppiated. prisms.) - let ee oc 64° 


Acetylferulic acid, C,H,(0.CO.CH,)(OCH,)C,H,.CO,H, is 
formed by boiling vanillin with acetic anhydride and sodium 
acetate, and crystallizes from alcohol in fine needles, melting at 
196°—197°. On heating with caustic potash it decomposes into 
acetic acid and ferulic acid (Tiemann and Nagai). 

Acetylisoferulie acid is obtained by heating isoferulic acid with 
acetic anhydride and crystallizes from alcohol in plates, melting 
at 199° (Tiemann and Will). 

Diacetyleaffeic acid, C,H,(0.CO.CH,)C,H,.CO,H, is formed 
when caffeic acid is heated with acetic anhydride and when 
protocatechualdehyde is heated with sodium acetate and acetic 
anhydride. It crystallizes from dilute alcohol in fine needles, 
melting at 190°—191°. On heating with caustic potash it 
decomposes into acetic acid and caffeic acid (Tiemann and 
Nagai). 

2412 Hesperetin, C,,H,,03, 1s obtained when hesperidin is 
heated to 115°—120° for three hours with 5 or 6 parts of 50 
per cent. alcohol, which contains 2 per cent. of sulphuric acid. 
It crystallizes from dilute alcohol in small plates with a satin 
lustre and from boiling water in flat, rectangular tablets, which 
are very slightly soluble in cold water, have a very sweet taste 
and melt at 226° with partial carbonization and decomposition. 
It dissolves readily in alkalis but is reprecipitated by carbon 
dioxide ; when boiled with caustic potash it decomposes into 
isoferulic acid and phloroglucinol, It has therefore the following 
constitution (Tiemann and Will) : 


CH. LOG “ OCH, HONG, H,. 
*‘\ CH—CH.CO. Oa 


Hesperidin, C,,H,,0,... This name was given by Lebreton to 
a crystalline body, which occurs in the fruits, and especially 


252 AROMATIC COMPOUNDS. 


the pulp and skin, of some species of the Aurantiacez.1 
It thus occurs in Citrus limonum, C. medica, C. aurantium, 
C. chinensis, C. longifolia, C. mandarin, and C. curassaviensis,? 
and also in their leaves, while it is not found in C. vulgaris, 
C. bigaradia, C. decumana (Pfeffer), It is best obtained 
from the officinal, dried unripe orange (fructus auranti 
immaturt) by washing the roughly powdered fruit with cold 
water, as long as the filtrate gives a precipitate with lead 
acetate. The residue is then extracted with 50 per cent. 
alcohol, to which 2 per cent. of caustic soda has been added, 
until the solution is no longer coloured. Hydrochloric acid is 
then added, the precipitate extracted with boiling 90 per cent. 
alcohol to remove coloured impurities and the residue dissolved 
in weak caustic potash, a little alcohol being then added and the 
product finally reprecipitated by carbon dioxide.’ 

Hesperidin forms an odourless and tasteless mass consisting of 
microscopic needles, which are very hygroscopic, but are scarcely 
soluble in water, only shghtly in alcohol and insoluble in ether; 
it may be obtained from boiling glacial acetic acid in larger 
needles. It readily dissolves in alkalis, as mentioned above; 
when it is heated for a few minutes with sodium amalgam and 
water, an orange-coloured solution is formed, im which hydro- 
chloric acid produces a precipitate, which forms a magenta-red 
solution in alcohol. This substance, which has also been obtained 
from naringin, has not been further investigated. It may prob- 
ably be related to the colouring matter of orange-peel, Berzelius 
having observed that this substance contains much hesperidin,* 
The latter decomposes on heating with dilute acids in a similar 
manner to naringin, into grape-sugar, isodulcite and hesperitin.® 

2413 Umbellic acid (1:3: 4). This name was formerly ap- 
plied to hydro-umbellic acid, the compound in question being 
called umbelliferonic acid, since it is formed when umbelliferon 
is heated with dilute caustic potash :° 


0.206 
HO.C,H< oe a ee Cte 
NCH CH | \CH=CH.C0.0H. 


1 Journ. Pharm. 1828, xiv. 877. 

2 Pfeffer, Ber. Deutsch, Chem. Ges. ix. 27; Paterno and Briosi, zbid. ix. 250; 
Tschirch, zbid. xiv. 948. 

3 Hoffmann, ¢bid. ix, 690; Tiemann and Will, zbid. xiv. 946. 

4 Berzelius, Jahresber. xxxii. 451. 

5 Will, Ber. Deutsch. Chem. Ges. xx. 1186. 

§ Reimer and Tiemann, zbid. xii. 993 ; Posen, ibid. xiv. 2744. 


UMBELLIC ACID. 253 





It forms a yellowish powder, which is readily soluble in alcohol 
and hot water and becomes converted into a resinous mass on 
continued boiling with water. 

Umbelliferon, C,H,O3, is formed by the distillation of the 
resins of various Umbelliferse,! such as that of the sumbul root 
(Huryangiwm sumbul), Asafcetida and especially that of the gal- 
tree, both of which are derived from species of Ferulacez. It is 
also obtained from the alcoholic extract of Daphne mezereum? 
and may be synthetically prepared by heating resorcinol and 
malic acid with sulphuric acid, the reaction corresponding to 
the formation of coumarin from malic acid and phenol.? 

It is almost insoluble in cold water, dissolves in 100 parts of 
boiling water and crystallizes on cooling in fine needles, which 
melt at 223°—224° and smell like coumarin when heated. It 
dissolves in concentrated sulphuric acid without decomposition, 
forming a solution which shows a dark blue fluorescence. Water 
and sodium amalgam convert it into hydro-umbellic acid. On 
fusion with potash, 8-resorcylic acid (Pt. IV. p. 359) is formed. 

Methylumbelliferon, Cj5H,(OCH;)O,, is formed when umbelli- 
feron is heated with methyl iodide, caustic potash and wood- 
spirit. It crystallizes in plates, which have a strong odour of 
coumarin when heated, and melts at 114° (Tiemann and Reimer). 

It yields two isomeric dimethylumbellic acids, behaving in 
this respect in an analogous manner to methylcoumarin. 

a-Dimethylumbellie acid, C,H,(0CH,),C,H,.CO,H, is obtained 
by heating a solution of methylumbelliferon and equal molecules 
of methyl iodide and sodium in wood-spirit, the methyl ether 
being then hydrolyzed. It crystallizes from alcohol in needles, 
- melting at 138°, and is converted into the following compound 
when it is heated to the boiling-point. 

B-Dimethylumbellic acid is also obtaimed by evaporating 
methylumbelliferon with caustic soda, heating the residue with 
methyl iodide and wood-spirit and hydrolysing the ether which 
is thus obtained. It crystallizes from hot water.in lustrous 
needles, melting at 180°—181°. 

Both these acids are converted by sodium amalgam and water 
into dimethoxyphenylpropionic acid, melting at 105°, and yield 
the same dimethyl-8-resorcylic acid on oxidation 4 

1 Sommer, Jahresb. Chem. 1859, 573 ; Hlasiwetz and Grabowski, Ann. Chem. 
Pharm. cxxxix. 100, bs Zwenger, Ann. Chem. Pharm. exv. 15. 

3 von Pechmann, Ber. Deutsch, Chem. Ges. xvii. 929. 


4 Tiemann and Will, ibid. xv. 2080; Will, zb¢d. xvi. 2115; Will and Beck, 
tbid. xix. 1777. 


254 AROMATIC COMPOUNDS. 


Acetylumbelliferon, C,H,(0.CO.CH,)O,, is obtained by heating 
umbelliferon with acetic anhydride or acetyl chloride,’ or resorey]- 
aldehyde with sodium acetate and acetic anhydride? It 
crystallizes from hot water in large prisms, melting at 140° and 
its aqueous solution shows a blue fluorescence. 

Metahydroxycoumarin, C,H,O,, is prepared by the action of 
sulphuric acid on a mixture of malic acid and quinol and 
crystallizes from boiling water in needles which melt at 248°— 
250°. Its solution does not show any fluorescence? 

Metamethoxycoumarin, C,xH,(OCH,)O,, is the methyl ether of 
the preceding compound, and is obtained by boiling methoxy- 
salicyl aldehyde with acetic anhydride and sodium acetate. It 
forms tabular plates, which melt at 103° and smell like 
coumarin.* 

Orthohydroxycoumarin, C,H,O,, has been prepared from 
catechol and malic acid; it crystallizes from alcohol in fine 
needles, which melt with decomposition at 280°—285°.5 

The constitution of the hydroxycoumarins is expressed by the 
following formule : 


Umbelliferon. Metahydroxycoumarin. Orthohe crass cornea 
CH—CH UGH CHa Gi: 
¢ ‘p-6o 6 ‘o-6o @ o-Co 
OH OH 
ee NA SR 
OH 
TRIHYDROXYPHENYLACRYLIC ACIDS, 
OH 
Ato 
6 -2——-OH 


\CH=CH.CO,H. 


2414 Only the substituted derivatives of these compounds, 
and the anhydrides, the dihydroxycoumarins, are known. 

Daphnetin, CjH,O,. The glucoside of this substance, daphnin, 
occurs in the bark of many species of Daphne, D. alpina, D. 
mezereum © and is decomposed on boiling with dilute acids or by 

1 Hlasiwetz, bid. iv. 450; Tiemann and Reimer, <bid. loc. cit. 

2 Tiemann and Lenz, ibid. x. 2216. 

3 Pechmann and Welsch, zbid. xvii. 1646. 

# Tiemann and Miiller, Ber. Deutsch. Chem. Ges. xiv. 1996. 

> Bizzari, ibid. xviii. Ref. 333. 


6 Vauquelin, Ann. Chim. Phys. lxxxiv. 173; Baer and Gmelin, Schweigg. 
Jowrn. xxxv. 1, 


TRIHYDROXYPHENYLACRYLIC ACID. 255 


the action of emulsin into glucose and daphnetin.' Its correct 
composition was determined by Rochleder * and its constitution 
has been ascertained by v. Pechmann® and by Will and Jung.* 
The former obtained it synthetically by heating pyrogallol and 
malic acid with sulphuric acid : 


CH - C_ CH=CH 
Fd Boa | 
HC OOH CH(OH).CH, HC CO—cO 
Pie | = | | +C0+3H,0. 
HC COH COOH COOH HC COH 
yee A ys, 
COH GOH 


It crystallizes from hot water in yellowish needles or prisms, 
which melt at 255°—256° and smell like coumarin on heating. Its 
aqueous solution is coloured green by ferric chloride, the colour 
being changed to red by sodium carbonate. If it be dissolved 
in a boiling solution of acid sodium sulphite and ammonia, and 
potassium ferricyanide added, a reddish yellow colouration is 
produced, while if ferric chloride be added to the bisulphite 
solution it is coloured deep blue.’ Its reddish yellow alkaline 
solution decomposes on standing or boiling. When daphnetin 
is heated with methyl iodide, caustic potash and alcohol, the 
following two compounds are formed : 

Mono-ethyldaphnetin, CjH,(OC,H,)O., crystallizes from dilute 
alcohol in lustrous plates, which melt at 155° and are soluble in 
alkalis. 

Drethyldaphnetin, C,5H,(OC,H,),0,, crystallizes from alcohol in 
needles melting at 72°, which dissolve slowly in a hot alkaline 
solution with a yellow colour and are reprecipitated by acids. 
Bromine converts it into diethylmonobromodaphnetin, which is 
converted by boiling with alkalis into diethyldaphnetilic acid, 
C,H,(OC,H,),0.4, which corresponds to coumarilic acid and forms 
crystals which resemble asbestos, and melt at 154°. 

Triethyldaphnetic acid, C,H,(OC,H,),C,H,CO,H, is formed 
when an alkaline solution of diethyldaphnetin is evaporated 
and the residue heated with alcohol and ethyl iodide. The 
ethyl ether is thus formed, and is then hydrolysed by alcoholic 

1 Zwenger, Ann. Chem. Pharm. exv. 1. 
2 Jahresb, 1863, 592. 
3 Ber. Deutsch. Chem. Ges. xvii. 929. 


4 Ibid. xvii. 1081. 
5 y, Pechmann and Cohen, 7bid. xvii. 2189. 


256 AROMATIC COMPOUNDS. 





potash. The acid forms crystals, melting at 193°. It is converted 
by water and sodium amalgam into triethylhydrodaphnetic acid, 
C,H,(OC,H,),C,H,CO,H, which forms crystals, melting at 85°. 

Triethyldaphnetic acid is converted into triethylpyrogallo- 
carboxylic acid (Pt. IV. p. 378) by the action of potassium 
permanganate (Will and Jung). 

Diacetyldaphnetin, C,H,(OCOCHS),0,, crystallizes from dilute 
alcohol in needles, which melt at 128°—129° (von Pechmann). 

Daphnin, C,H,(OC,H,,0;)OH(C,H,O,) + 2H,0, crystallizes 
from hot water in rectangular, prisms which become anhydrous 
at 100° and form a yellow solution in alkalis. 

2415 Asculetin, C,xH,O, + H,O, occurs in small quantity in 
the bark of the horse-chestnut (4sculus hippocastanum),’ accom- 
panied by its glucoside, esculin, from which it can be readily 
obtained by decomposition with acids or emulsin.? 

It crystallizes from boiling water in very fine, lustrous needles, 
which lose water and become yellow at 100° On heating it 
smells like coumarin and melts with decomposition at 270°. Its 
yellow aqueous solution has a faint blue fluorescence and is 
coloured deep green by ferric chloride ; it forms a yellow solution 
in alkalis. It combines with acid sodium sulphite to form the 
compound C,H,0,-+ NaHSO,,° which probably has the following 
constitution : 

/ —c<oy 
CH OB) | 
CH,—CH, 


It crystallizes in small needles with a satin lustre and forms a 
solution, which becomes red when heated with ammonia and 
exposed to the air, the colour changing to azure blue and finally 
to blood-red, a splendid fluorescence being also produced. 

When the sulphite compound is decomposed by sulphuric 
acid, hydro-wsculetin, C,H,O,, is obtained. This compound was 
named paresculetin by Rochleder, who considered it to be 
isomeric with esculetin. It is readily soluble in water, crystal- 
lizes badly and also gives a blue colouring matter with ammonia, 
a solution of which dries to an amorphous mass possessing a 
splendid violet metallic lustre. The solution of the original 
compound alters on standing and yields a brown mass with a 

1 Rochleder, Jahresb. Chem. 1863, 589. 

2 Rochleder and Schwarz, Ann. Chem. Pharm. lxxxviii. 356. 


3 Rochleder, loc. cit. ; Liebermann and Knietsch, Ber. Deutsch. Chem. Ges, 
xiii, 1591. 


METHYLASCULETIN. 257 | 





faint green lustre on evaporation ; traces of alcohol colour the 
solution pink and impart to it a splendid cinnabar-red fluor- 
escence, this reaction being so delicate that distilled water can thus 
be distinguished from spring water containing calcium carbonate. 

Methylesculetin, C,H,(OCH,)O3, is formed, together with 
following compound, when esculetin is heated with a solution of 
caustic potash and methyl iodide im wood-spirit and crystallizes 
in lustrous needles, which melt at 184° and dissolve in alkalis to 
form a solution showing a green fluorescence. 

Dimethylesculetin, C,H,(OCH,),O,, crystallizes from hot 
water in lustrous needles, melting at 144°. 

The following compounds have been obtained in a similar 
manner : 

Ethylesculetin, C,H,(OC,H,)O., forms colourless or yellowish 
erystals, which melt at 143°; its alcoholic solution shows a 
blue fluorescence. 

Diethylesculetin, C,H,(OC,H,),0,, crystallizes in silvery plates, 
melting at 109°. It is converted by bromine into diethylmono- 
bromesculetin, which crystallizes in lustrous needles, melting at 
169°, and on heating with alcoholic potash yields diethoxy- 
coumartlic acid, C,,H,,0;, a substance which forms fine needles 
and melts at 195°. 

a-Triethylesculetic acid, C,H,(OC,H,),C,H,CO,H, is formed 
when diethylzsculetin and equal molecules of ethyl iodide and 
sodium are dissolved in absolute alcohol and heated on the 
water-bath for four or five hours. The ethyl ether thus 
obtained, which crystallizes in thick yellow prisms, melting at 
51°, is hydrolyzed with alcoholic potash. The free acid forms 
crystals, which melt at 102°—103°; when it or its ether is heated 
to the boiling-point, the following isomeric compounds are formed. 

B-Triethylesculetic acid. The ether of this acid is also formed 
by using a slight excess of ethyl iodide in the above method 
and heating for eight hours. It crystallizes in lustrous tablets, 
melting at 75° ; the acid forms silvery crystals, melting at 144°. 

Both acids are converted by sodium amalgam and water into 
triethoxyphenyl-propionic acid, C,H,(OC,H,).C,H,CO,H, and 
on oxidation yield a triethoxybenzoic acid, C,H,(OC,H,),CO,H, 
which decomposes on heating with lime into carbon dioxide and 
~hydroxyquinol triethyl ether. 


1 Liebermann and Mastbaum, ibid. xiv. 474. 


2 Will, Ber. Deutsch. Chem. Gres. xvi. 2106 ; Will and Albrecht, ibid. xvii. 
2108 ; Will and Pukali, zdid. xx. 1119. 


258 AROMATIC COMPOUNDS. 





Diacetylesculetin, CyH,(O.CO.CH,;),0O,, crystallizes from 
alcohol in prisms, melting at 133°—134° (Liebermann and 
Mastbaum). 

The constitution of ssculetin has not yet been determined 
with certainty, since the position of the acrylic acid residue is 
still unknown; it must however be represented by one of the 
following three formule : 


CH —GE. Gl ot becess C4 | GH==C Ei 
HOY” o.co c p.co HO” \o.60 
: BO } HO 


OH 


4isulin, C,H,(OH)(OC,H,,0,)C,H,O, The apothecary 
Frischmann was the first to observe that the yellow-coloured 
extract of the skin of horse-chestnuts shows a blue reflection * 
and Remmler prepared the compound which gives it this pro- 
perty in a tolerably pure condition.? Raab, another apothecary, 
then re-discovered it and named it schillerstof;? while Martius 
gave it the name of bicolorin and Kastner termed it polychrom ; * 
Berzelius then proposed the name zesculinic acid, which was 
finally changed into esculin. According to Jonas, it is found in 
the bark in largest quantity im spring before the buds are open,® 
and also occurs in the root bark of the American wild jasmine 
(Gelsemiwm senvpervirens).® 

In order to prepare it, horse-chestnut bark is extracted with 
boiling water, the solution precipitated with lead acetate, the 
filtrate heated with sulphuretted hydrogen, again filtered and 
evaporated. The esculin separates out and is purified by re- 
crystallization from alcohol and water.’ The bark may also be 
extracted with dilute ammonia, the solution evaporated and the 
residue mixed with alumina and extracted with 95 per cent. 
alcohol. The esculin, which crystallizes out, is shaken up with 
water and ether and then washed with benzene.§ 

Properties.—Ilt forms small prisms, containing 1} molecules of 
water, which is lost at 120°—130°; it melts at 160° with decom- 


1 Orell’s Chem. Journ. v. 5. 


* “Ueber die Doppelfarbe der wilden Kastanienrinde”; Taschenbuch. /f. 
Scheidekunde und Apoth. 1785. 3 Archiv fiir Naturkunde, x. 121. 

* Ann. Chem. Pharin. xiv. 190. 5 Ibid. xv. 266. 

6 Sonnenschein, Ber. Deutsch. Chem. Ges. ix. 1182. 

7 Rochleder and Schwarz, Ann. Chem. Pharm. \xxxvii. 186. 

8 Fairthorne, Jahresber. Chem. 1872, 788. 


ZESCULIN, 259 





position! and decomposes at 230° into zsculetin and glucosan.? 
It dissolves, according to Trommsdorff, in 24 parts of boiling 
alcohol of sp. gr. 0°798, in 672 parts of water at 10°5° and in 576 
parts at 25°, being more readily soluble in alkalis. The aqueous 
solution shows a blue fluorescence, which is rendered more 
prominent by the addition of alkalis. A very dilute solution, 
for example, only showing a faint shimmer, acquires a splendid 
sky-blue fluorescence when spring water is added to it. One 
part of zsculin can thus be detected in 15,000,000 parts of 
water (Trommsdorff). Acids destroy the fluorescence, but it 
reappears on neutralization. Adsculin dissolves in a small 
quantity of nitric acid with a yellow colour, which is changed 
to blood-red by ammonia; 0°2 mgrm. can thus be detected 
(Sonnenschein). 
1 Zwenger, ibid. xc. 65. 


2 Schiff, Ber. Deutsch. Chem. Ges. xiv. 303. 
3 Ann, Chem. Pharm. xiv. 189, 


260 AROMATIC COMPOUNDS. 





PHENYLPROPIOLIC GROUP. 


2416 Phenylpropiolic acid, C,H,,C=C.CO,H, has been pre- 
pared by Glaser by the combination of carbon dioxide with 
sodium phenylacetylene, the action of sodium and carbon dioxide 
on #-phenylbromethylene (p. 33) and by heating a-bromo- 
cinnamic acid with alcoholic potash, and it is formed in a 
similar manner from @$-bromocinnamic acid.2 It is readily 
soluble in alcohol and ether, only slightly in water, from which 
it crystallizes in long needles, which melt at 137° and are only 
slightly volatile with steam, melting under water at 80°. When 
it is distilled with baryta or heated to 120° with water, it decom- 
poses into phenylacetylene and carbon dioxide. Sodium amalgam 
and water convert it into phenylpropionic acid without the 
production of cinnamic acid # and it combines with bromine to 
form phenyltetrabromopropionic acid, C,H,.CBr,.CBr,.CO,H, a 
substance which has not yet been investigated. 

Barium phenylproprolate crystallizes with various amounts of 
water, according to the temperature at which it is deposited. If 
the solution be allowed to evaporate at a low temperature over 
sulphuric acid, broad plates of (C,)H,O,),Ba+3H,O separate 
out; at the ordinary temperature, fascicular groups of broad 
needles, containing two molecules of water, are obtained, while 
quadratic tablets of 2(C,H,O,),Ba + H,O are formed when a 
hot, saturated solution is allowed to cool slowly. Finally, if this 
salt be boiled with alcohol, fine needles of the anhydrous salt 
are obtained. 

Copper phenylpropiolate, (C,H,;0,),Cu + 4H,O, crystallizes 
from hot water in blue, rhombic plates, which become a green 
at 80°—90°, with loss of water, carbon dioxide being simul- 


1 Ann. Chem. Pharm. cliv. 140. 
2 Barisch, Jowrn. Prakt. Chem. [2], xx. 180. 
. Erlenmeyer, Ber, Deutsch. Chem. Ges. xvi. 152. 


PHENYLPROPIOLIC GROUP. 261 





taneously evolved and phenylacetylene, which may be recognized 
by its smell, formed. 

Orthonitrophenylproprolic acid, C,H,(NO,)C,.CO,H, is readily 
formed when orthonitrophenyldibromopropionic acid is dissolved 
in an excess of caustic soda and the solution allowed to stand 
for some time.! 

On the addition of hydrochloric acid it separates out in 
brilliant plates, which crystallize from hot water in almost 
colourless needles, which decompose suddenly at 155°—156°, 
leaving a voluminous residue. Its alkali salts crystallize badly ; 
the silver salt is a white precipitate, which explodes very 
violently on heating. 

The acid decomposes on boiling with water into orthonitro- 
phenylacetylene and carbon dioxide, while isatin (p. 73) is 
formed when it is boiled with alkalis, If its alkaline solution be 
heated with a little grape-sugar or some other reducing agent, 
pure indigo-blue separates out, the yield of which amounts to 40 
per cent. of the acid employed, while 68 per cent. are required 
by theory ; the loss is mainly due to the formation of isatin 
(Baeyer).? 

This reaction is employed to fix indigo in calico-printing ; 
potassium xanthate, which was found by H. Caro to be the best 
reducing agent for the purpose, is printed on the cloth together 
with caustic soda and the acid, the material being then dried 
and steamed, 

Hithyl —orthonitrophenylpropiolate, C,H,(NO,)C,.CO,.C,H,, 
crystallizes from ether in large tablets, melting at 60°—61", 

Paranitrophenylpropiolic acid has been prepared by paranitro- 
phenyldibromopropionic acid, which is formed by the combination 
of bromine with paranitrocinnamic acid,? This substance, how- 
ever, always yields some of the original paranitrocinnamic acid in 
addition to the nitrophenylpropiolic acid on treatment with 
alkalis, the bromine being simply eliminated, and it is therefore 
better to combine ethyl paranitrocinnamate with bromine and 
treat the ether in hot alcoholic solution with caustic potash.* 

Paranitrophenylpropiolic acid forms a silky, yellow mass or 
yellow needles, which melt at 198° with evolution of gas and 
decompose into paranitro-acetylene and carbon dioxide when 
heated to 140° with water. 


1 Baeyer, Ber. Deutsch. Chem. Ges xiii, 2279. 

2 See also Miiller, Ann. Chem. Pharm. cexii. 148. 

3 Drewsen, ibid. ecxii. 150. 

4 Miiller, cbid. cexii. 188 ; Perkin, Jowrn. Chem. Soc. 1886, i. 440. 


262 AROMATIC COMPOUNDS. 


Lthyl paranitrophenylpropiolate, C,H,(NO,)C,.CO,. C,H, 
crystallizes in long, flat needles, melting at 126°. 

Orthamidophenylpropiolic acid, O,H,(NH,)C,.CO,H, is’ 
obtained by the addition of ferrous sulphate solution to a 
solution of orthonitrophenylpropiolic acid in an excess of 
ammonia, It forms yellowish, microscopic needles, which are 
insoluble inwater and decompose on boiling with water, ortha- 
mido-acetophenone being formed.? 

Isatogenice acid, C,H;NO,, is formed, as already mentioned 
(p. 76), when orthonitrophenylpropiolic acid is dissolved in 
sulphuric acid : 

C=C.CO,H CO 
CHC ; = CHC > 0.C0,H. 
NO, PS b 


When the solution is poured into water, the isatogenic acid 
decomposes instantaneously into carbon dioxide and isatin. If, 
however, ferrous sulphate be added to the sulphuric acid solu- 
tion, indoin, C;,H,,N,O,, a blue colouring matter, which will be 
described along with indigo, is formed. 

Lihyl isatogenate, C,H,(C,H;)NO,, is formed by the action of 
sulphuric acid on ethyl orthonitrophenylpropiolate and crystal- 
lizes in yellow needles, melting at 115°? 

2417 Indoxylic acid, C,H,NO,. The ethyl ether of this acid 
is formed by the action of ammonium sulphide on ethyl ortho- 
nitrophenylpropiolate or of zinc and hydrochloric acid on ethyl 
isatogenate, the ether of the pseudo-acid being the first product 
and changing into that of indoxylic acid, just as pseudo-isatin 
changes into isatin : 


0 | 
SE ae BOA WAH, = EO? 


CO C(OH) 
C,HZ .) ) SCHCO,.CLH..= G,HiGt «6 SC. Costa 
\nH” N2NH 
In order to prepare the acid, the ether is brought into caustic 
soda, which has been treated with a little water and heated to 
180° and the product decomposed with dilute sulphuric acid, the 


1 Baeyer and Bloem, Ber. Deutsch. Chem. Ges. xv. 2147. 
* Baeyer, tbtd. xiv. 1741 ; xv. 780. 


INDOXYLIC ACID. 263 


indoxylic acid being thus precipitated as a crystalline powder, 
which melts at 122°—123° with copious evolution of gas.1 Its 
dilute alkaline solution rapidly absorbs oxygen with formation of 
indigo-blue, which is also formed by the action of acid oxidizing 
agents on the acid, as, for example, when its alkaline solution is 
heated with orthonitrophenylpropiolic acid. 

Ethyl indoxylate forms thick, colourless prisms, melting at 
120°—121°, and dissolves in alkalis without decomposition, form- 
ing a solution from which it is reprecipitated by carbon dioxide. 
On heating with sulphuric acid it is converted quantitatively 
into indigosulphonic acid. When it is boiled with water, indoxyl 
is formed, which combines with isatin in a hot solution to form 
indigorubin, an isomeride of indigo. 

Lthylindoaylie acid, C,H,(OC,H;)NCO,H. The ethyl ether 
of this body is the product of the action of ethyl iodide and 
caustic potash on ethyl indoxylate, which therefore behaves as a 


phenol: 
OK 


wv, S 
CHK 0.00, 0H, POH I= 


OC,H, 
ne 


HK a “Neco, OH, + KI. 


It forms large, colourless crystals, melting at 98°. In order to 
prepare the acid, the alcoholic solution of the ether is boiled 
with baryta and then acidified. It crystallizes in small plates, 
which melt at 160°. It does not oxidize to indigo in alkaline 
solution, but the oxidation may be brought about by ferric 
chloride and hydrochloric acid. Nitrous acid converts it mto 
ethylnitroso-indoaylic acid, C,H,(OC,H,)N(NO)CO,H, which 
crystallizes from alcohol in large, flat, golden-yellow needles. 

Indoxanthic acid, C,H,NO, The ethyl ether is formed when 
ethyl indoxylate is carefully oxidized with ferric chloride and 
crystallizes from ether in straw-yellow needles or long, mono- 
symmetric prisms, which reflect the green and yellow rays and 
form a deep yellow-coloured solution in water. If this solution 
be treated with sodium nitrite and then sulphuric acid, ethyl 

1 Baeyer, Ber, Deutsch. Chem. Ges. xiv. 1742 ; Forrer, ibid. xvii, 975. 
283 


264 AROMATIC COMPOUNDS. 


nitroso-indoxanthate, C,,H,)(NO)NO,, is formed; it crystallizes 
in yellowish needles or tablets and gives Liebermann’s reaction. 
Indoxylic acid and the ethers of indoxanthic acid are oxidized .to 
ethyloxalanthranilic acid by chromic acid solution, while this 
yields the original acid on reduction. Ethyl indoxanthate has, 
therefore, probably the following constitution, which explains the 
formation of ethyl oxalanthranilic acid in a simple manner :! 


CO CO.OH. 
O,H,< C(OH)CO,, C,H, 2O# CHK 
NH. NH.CO.CO,.C,H, 
The formation of imdigo-blue from indoxylic acid can be 
readily explained by assuming that pseudo-indoxylic acid is first 
formed and then loses carbon dioxide and hydrogen: 








CO 00 
He Secu co. No 
C, nee oy ; CH a We 
420= +2CO, + 2H,0. 
CO 
CHS  SCHCO.H Sa | 
6 NH 2 OH ee 


In the conversion of orthonitrophenylpropiolic acid into indigo, 
isatogenic acid is probably the first product and then undergoes 
reduction : 


CO 
COL CeL eS GCOL CHett oO Ne 
6 NN 2 6 ’ NH 
ae + 200, + 2H,0. 
CHa a 
6 oR hae 2 6 can ve 


SUBSTITUTED INDOLS, 0,H,N. 


2418 Skatol, C,H,N, was discovered by Brieger in human 
excrements (TO oxatos, Meeces), accompanied by a little indol, 
but is not present in those of the dog, either during a flesh or a 
bread diet.? Tappeiner found it in the paunch of the cow, while 
indol alone occurs in both the large and small intestine. In the 


1 Baeyer, Ber. Deutsch. Chem. Ges. xv. 775. 2 Ibid. x. 1027. 


SKATOL, 265 





horse, on the other hand, the latter occurs in the small intestine, 
phenol alone in the large intestine, and skatol in the colon! The 
latter is formed, together with indol, by the putrefaction of ege 
albumen and when this is fused with caustic potash. It is 
also a product of the putrefaction of flesh,® especially in the 
presence of the pancreatic secretion,* and is formed in still 
greater abundance from the brain of the ox.? 

Baeyer found that it may also be obtained, together with indol, 
from indigo, by reducing this to the yellow compound, which 
has already been mentioned, and heating this product with zinc 
dust. O,. Fischer and German prepared it by heating aniline 
zinc chloride with glycerol : ’ 


C.H,N + C,H,O, = C,H,N + 3H,0. 


Fileti prepared it from orthonitrocumic acid, C,H,(NO,)CH 
(CH,),CO,H, by distilling the barium salt with iron filings or 
zinc dust, but obtained a better yield by heating a mixture 
of this salt with orthamidocumic acid and caustic baryta.® A 
mixture of orthonitrocumene and orthamidocumene is formed 
and undergoes the following decomposition : 


on/oe on oe 
HK ot +0 at ~\ cH, = ss 
NH 


2 


CH, 


SOK. Sou + 4H,0. 


Its constitution has been decisively determined by E. Fischer. 
When propidenephenylhydrazone, an oily liquid, which is formed 
by the action of phenylhydrazine on propionaldehyde, is mixed 
with an equal weight of powdered zinc chloride, a vigorous 
reaction ensues, the mixture being finally heated to 180° for one 
or two minutes : 


ata es 
C,H, N,H—=CH,CH,CH, = OH, SCH’ + NH, 
NH 


1 Ber. Deutsch. Chem. Ges. xiv. 2382. 

2 Nencki, Journ. Prakt. Chem. [2], xvii. 98. 

3 KE. and i. Salkowski, Ber. Deutsch. Chem. Ges. xii. 648 ; xviii. 79. 
4 Brieger, 2bid. xii. 1985. 

5 Nencki, Hoppe-Seyler’s Zeitschr. iv. 371. 

6 Ber. Deutsch. Chem. Ges. xiii. 2339. 

7 Ibid, xvi. 710. 8 Ibid. xvi. 2927. 


266 AROMATIC COMPOUNDS. 


The skatol is purified by distillation with steam.’ It also 
occurs among the products of the distillation of strychnine with 
lime.2 It crystallizes from hot water or better from petroleum- 
spirit in dazzling white plates, melts at 95° and boils at 
265°—266°.. According to Nencki and Brieger it possesses a 
persistent fxecal odour, while Baeyer describes the odour as 
simply sharp, and is confirmed by O. Fischer and German, who, 
however, add that in the finely divided condition, as on the 
hands and clothes, it has a most unpleasant small. HE. Fischer, 
on the other hand, states that even after bemg converted into 
the nitrosamine and again prepared from this it possesses an 
intense adhering odour of feeces.? 

A splinter of. pine-wood moistened with strong hydroshiees 
acid is not coloured by an aqueous or alecholic solution of 
skatol, while if the splinter be moistened with a hot alcoholic 
solution and be then brought into cold concentrated hydrochloric 
acid, it is coloured cherry-red and finally dark violet. 

When sodium nitrite is added to a solution of skatol in cold 
glacial acetic acid, a dark brown colouration is produced and the 
nitrosamine is precipitated by the addition of water as a yellow 
oil, which solidifies in a freezing mixture to a crystalline mass, 
It gives Liebermann’s reaction and is reconverted into skatol by 
zinc dust and dilute acids. Its formation is very characteristic 
and can be employed for the distinction and separation of skatol 
from indol and methylketol (E. Fischer). 

The picrate is precipitated in red needles when hot aqueous 
solutions of picric acid and skatol are mixed. 

Skatolsulphurie acid, C,1,NSO,H, appears as the potassium 
salt in the urie when skatol is taken internally; it has been 
observed by J. G. Otto in considerable quantity in a case of 
diabetes, and obtained from boiling alcohol in crystals. 

Hydroskatol, C,H,,N, is formed when zinc dust and hydro- 
chloric acid are gradually added to a boiling alcoholic solution 
of skatol and'is an oily liquid, which boils at 231°—232°, smells 
somewhat like quinoline and piperidine and readily combines 
with acids. Its platinichloride forms fine needles, only slightly 
soluble in water and its nitrosamine is an oily liquid.° 


1 Ann. Chem. Pharm. eexxxvi. 137. 

2 Stoehr, Ber. Deutsch. Chem. Ges. xx. 1108. 

Basel s Kopp remarks on the compound ethers: ‘‘ The odour of these compounds 
is difficult to define and is often differently described by different Investigators 
(butyric ether smells to some like old cheese, to others like pine- apple),” “Pogg. 
Ann. |xxii. 259, 4 Ber. Deutsch. Chem. Gres. xvii. Ref. 380. 

° Wenzing, Ann. Chem. Pharm. ccexxxix. 239. 


METHYLKETOL. 267 





2419 Methylketol, CJH,N, is formed by the action of zinc 
dust and ammonia on orthonitrobenzylmethylketone, this being 
reduced to amidobenzylmethylketone, which then passes into 
methylketol with elimination of water, the changes probably 
taking place as follows :} 


Te CUR Ee 
“heey ee 


SEAN 
OR 5 BK >C(OH)CH, = 


CH 
ae + H,0. 


It is also obtained when acetonephenylhydrazone is heated 
with five parts of zine chloride, at first on the water-bath and 
finally to 180° in an oil bath :? 


Vee ok: 
Rite ttt Noa HK a 


Methylketol crystallizes from hot water in needles and from 
alcohol in plates, which melt at 60° and have a similar smell to 
indol. It melts at 272° and its vapour has a sp. gr. of 4°75 ; 3 it 
colours a pine splinter moistened with hydrochloric acid red, 
similarly to indol ; nitrous acid produces a yellow colouration in 
its aqueous solution, followed by an amorphous, yellow precipitate, 
while, when sodium nitrite is added to a solution in glacial acetic 
acid,a dark red colouration is produced and water then produces 
a reddish brown precipitate, which does not give Liebermann’s 
reaction. It differs from indol and skatol in forming a platini- 
chloride, (Cj, H,N.HCl),PtCl,, which crystallizes in yellow needles. 
Its picrate crystallizes in fine, yellowish-red needles. Methyl- 
ketol is oxidized by potassium permanganate to acetorthamido- 
benzoic acid (Pt. IV. p. 239), which is therefore formed in an 
analogous manner to oxalorthamidobenzoic acid from carbostyril 
(p. 223). 

Amidomethylketol. When crystallized sodium acetate and 
then an alcoholic solution of methylketol are added to a solution 
of diazobenzene chloride, methylketolazobenzene is formed; it 
separates from hot petroleum-spirit in small, compact, red crystals 


~ No—cHy, + NH, 


1 Baeyer and Jackson, Ber. Deutsch. Chem. Ges. xiii, 187 ; Jackson, ibid. xiv. 
79 


2 Fischer, Ann. Chem. Pharm, ecxxxvi. 126. 
3 Treadwell, Ber. Deutsch. Chem. Ges. xiv. 1466. 


268 AROMATIC COMPOUNDS. 


and melts at 115°—116°. It is converted into amidomethylketol 
by the action of hydrochloric acid and tin : 


C—_N=N.C,H, ONE; 
CHL >C.CH, + 4H = CHC > >C.CH, + H,N.C,H,. 


This crystallizes in small plates, which melt at 112°—113° 
and rapidly become coloured pink and finally dark red in the 
air, ‘The hydrochloride forms well-developed prisms. On heat- 
ing with zinc dust and hydrochloric acid the following compound 
is obtained.? 

Hydromethylketol, C,H,,N, may also be prepared by heating 
methylketol with tin and hydrochloric acid and is a colourless, 
oily liquid, which has a characteristic pungent odour, resembling 
that of piperidine, and boils at 227°—228° (Wenzing). It is a 
strong base and forms a platinichloride, which crystallizes in 
octohedra. Acetic anhydride acts upon it with formation of 
acetylhydromethylketol, C,H,,NCO.CH,, which crystallizes from 
petroleum-spirit in concentrically grouped needles, which melt 
at 55°—56°. 

Nitrosohydromethylketol, CjH,,N.NO, is formed when sodium 
nitrite is added toa solution of hydromethylketol m hydrochloric 
acid (Jackson) and separates from petroleum-spirit in compact 
yellow crystals, which melt at 54°—55°, It is reconverted into 
hydromethylketol by the action of tin and hydrochloric acid and 
gives Liebermann’s reaction, so that it probably possesses the 
following constitution : 


oy 
*CH.CH,. 
AC No 
| 
NO 
2420 Dimethylindol, CoH /L Os is obtained by heat- 
N —CH, 


ing acetonemethylphenylhydrazone, O,H;.N,(CH,)—C(CH,),, 
with zine chloride to 130° and crystallizes from hot petroleum- 
spirit in fine needles, which melt at 56°, volatilize without 
decomposition and are slightly soluble in water, readily in 
alcohol and concentrated hydrochloric acid. This last solution 
colours a pine splinter in the same way asindol. Dimethylindol 
picrate crystallizes from benzene in fine, dark red needles.? 


1 Wagner, Ann. Chem. Pharm. cexlii. 383. 2 Degen, ibid. cexxxvi. 153. 


DIMETHYLINDOL. 269 


L3-Methylindol, CH,.C,H Kes fF ont is prepared by heat- 
3° 6 *\ NH” 


ing B3-Pr2-methylindolcarboxylic acid, a substance which will 
be subsequently described. It crystallizes from hot water in 
colourless needles, which melt at 58°5° and cannot be dis- 
tinguished from indol by the smell or other general properties.’ 

In addition to these bodies, other substituted indols are also — 
known, some which will be subsequently described. They are 
designated by the following nomenclature, which has been 
proposed by E. Fischer : 

“ The nitrogenous ring of indol, which is actually a pyrrol ring, 
receives the symbol Pr and the numbering of the component 
atoms commences in the pyrrol ring at the nitrogen and in the 
benzene ring at the corresponding carbon atom, as shown in the 
following diagram :” shri Oe 


0% SN ; 


In order to avoid errors, an ” is added as an index to the 
number representing the position of the nitrogen atom, when 
necessary ; thus we have the following names :? 


Pr 12- “OH Prilé;2- Clix, lindol. 
aé Nou iG pee CH, 
Ne tidine Tele 
Pr 2-Methylindol or Ee Pr 3-Methylindol or cee 
CH  SCcH cH \cH 
6 ‘\ NH rr 3 *\N NH ©, 


If substitution take place in the aromatic nucleus, the symbol 
B is prefixed to the number. The formula of B3-methylindol is 


therefore : Cn G 
TANT ae 
CE heal 2) aN 
bebiiay: 
SNA 
Oho M. 


1 Raschen, Ann. Chem. Pharm. ccxxxix. 223. 2 Ibid. eexxxvi. 121. 


270 AROMATIC COMPOUNDS. 


INDOLCARBOXYLIC ACID, C,H,NO,,. 


2421 The ethyl ether of this acid is formed when the pheny]l- 
hydrazone of pyroracemic acid is heated to 195° with zine 
chloride : 


_C,H,.N HeCHY = 
Cr elie 


can "Ne CO,.0,H, + NH. 

It crystallizes in white prisms and is readily hydrolysed by 
heating with a little alcohol and fairly concentrated caustic potash 
solution. On the addition of dilute sulphuric acid to the solu- 
tion, the indolcarboxylic acid is precipitated as a crystalline 
mass; it separates from boiling water in long, fine needles, which 
melt a 200° to a red liquid and Gescmpoae. at 230° into carbon 
dioxide and indol, which, however, for the most part undergoes 
a further change at this temperature. 

It does not give any colouration with a pine splinter moistened 
with hydrochloric acid. The picrate separates in golden-yellow 
needles when the acid is brought together with picric acid in 
ethereal solution. When nitric acid is added to its solution in 
glacial acetic acid, yellow crystals are precipitated after some 
time, which form a deep red solution in alkalis.1 

Methylindolearboxylic acid, C,H,(NCH,)CO,H, is formed by 
the action of hydrochloric acid on the methylphenylhydrazone 
of pyroracemic acid and crystallizes from hot alcohol in white 
needles, which melt at 212° and gradually decompose into 
carbon dioxide and methylindol. 

Hithylindolearboxylie acid, C,H,(NC,H,)CO,H, forms colourless 
needles, melting at 183°. 

Phenylindolearboxylic acid, C,H,(NC,H,)CO,H. When pyro- 
racemic acid and diphenylhydrazine are brought together in 
ethereal solution, the mixture becomes warm and the diphenyl- 
hydrazone of pyroracemic acid separates out after a short time in 
crystals, which readily form a yellow solution in hot benzene, 
less readily in ether and cold alcohol and crystallize from hot 


1 Fischer, Ann. Chem. Pharm. ccxxxvi. 141. 


INDOLCARBOXYLIC ACID. 271 





alcohol in white needles, melting at 145°. If it be dissolved in 
glacial acetic acid, fuming hydrochloric acid added and the 
mixture heated on the water-bath, phenylindolcarboxyliec acid 
is formed and crystallizes from dilute alcohol in white needles, 
melting at 176° 

Benzylindolearboxylic acid, C,H,(NCH,.C,H,)CO,H, has been 
obtained from benzylaniline by reducing the nitrosamine with 
zinc dust and glacial acetic acid and treating the resulting 
benzylphenylhydrazine with pyroracemic acid. The oily product 
thus obtained yields benzylindolcarboxylic acid on heating 
with hydrochloric acid. It crystallizes from hot glacial acetic 
acid in compact needles, which melt at 195° with evolution 
of gas. 


1 Fischer and Hess, Ber. Deutsch. Chem. Ges. xvii. 559. 
2 Antrick, Ann. Chem. Pharm, cexxvii. 360. 


272 AROMATIC COMPOUNDS. 





THE CYMENE GROUP. 


2422 The following hydrocarbons of the general formula C,,H,, 
are known: 


s-Tetramethylbenzene or durene 
a-Tetramethylbenzene or isodurene boagcn) : 
v-Tetramethylbenzene or prehnitene 


Ethylparaxylene 
s-Ethylmetaxylene JOHs 

Opals GMa! 
a-Hthylmetaxylene § SCH > 
a-Hthylorthoxylene : 
Paradiethylbenzene 
Metadiethylbenzene i CoH (Cols) 
Paramethylpropylbenzene or cymene CH, 
Orthomethylpropylbenzene or orthocymene \ CHK 
Metamethylpropylbenzene or metacymene CH, 


Para-isocymene 


CH, 
Meta-isocymene t CcHi<CH(CH,), 


Butylbenzene, C,H;.C,Ho. 
a-Isobutylbenzene, C,H,.CH,.CH(CH,).. 


B-Isobutylbenzene, C,H, CH<6 : 
275 


Cymene, which occurs in nature, is the member of this group 
with which chemists have been acquainted for the longest time. 
The others have been artificially prepared and some of them have 
also been found in rock-oil and in the products of the dry 
distillation of resin and coal. 


THE TETRAMETHYLBENZENES. 273 


THE TETRAMETHYLBENZENES, (,H,(CH,),. 


s-Tetramethylbenzene (1:2:4:5) was first prepared by Fittig 
and Jannasch by the action of sodium on a mixture of methyl 
iodide and bromopseudocumene and named duvene, because it 
differs from the benzenehydrocarbons, which were then known, 
in being solid (dwrus) at the ordinary temperature! A better 
yield is obtained by employing dibromometaxylene? or dibro- 
moparaxylene.* It is also formed by the action of methyl 
chloride on a mixture of toluene and aluminium chloride,* 
orthoxyléne, accompanied by small quantities of its two iso- 
merides, being the first product. This yields pseudocumene 
almost exclusively on further methylation and the latter is 
then converted into durene, which can therefore be readily 
prepared by passing methyl chloride, dried by sulphuric acid, 
into a mixture of one part of aluminium chloride and five parts 
of pseudocumene at a temperature of 75°—85°5 

Durene is also formed in small amount, when oil of turpentine 
is passed through a red-hot tube ® and occurs in Baku petroleum ? 
and coal-tar.$ 

It is readily soluble in alcohol, ether and benzene, and 
crystallizes from the last two in large tablets or prisms, while it 
separates from petroleum-spirit in clear, strongly refractive 
monosymmetric crystals. It possesses an odour resembling that 
of camphor, melts at 80°, boils at 191°—192° and gradually 
-sublimes even at the ordinary temperature in plates or tablets. 
On heating with phosphorus pentachloride, the chloride 
C,H,(CH,Cl), is formed, which separates from ether in 
crystals, melting at 144°, which are converted into the alcohol, 
C,H,(CH,.OH),, by continued heating with very dilute caustic 
potash solution; the latter forms a bitter, elastic mass, only 
slightly soluble in water. 

1 Zeitschr. Chem. 1870, 161. 

2 Jannasch, Ber. Deutsch. Chem. Ges. vii. 692 ; Gissmann, Ann. Chem. Pharm. 
ecxvi. 200. 

3 Jannasch, Ber. Deutsch. Chem. Ges. x. 1354. 

4 Friedel and Crafts, Ann. Chim. Phys, [6], i. 449; Ador and Rilliet, Ber. 
Deutsch. Chem. Ges. xii. 329. 

5 Jacobsen, zbid. xiv. 2624. 

6 Montgolfier, Ann. Chim. Phys. [5], xix. 164. 

7 Markownikow, Ann. Chem. Pharm. ccexxxiv. 114. 


8 Schulze, Ber. Deutsch. Chem. Ges. xviii. 30. 
9 Colson, Bull. Soc. Chim. xlvi. 198. 


274 AROMATIC COMPOUNDS. 


Bromodurene, C, HBr(CH,),, crystallizes from hot alcohol in 
nacreous plates, melting at 61°. 

Dibromodurene, C,Br,(CH,),, forms long, thin needles, melting 
at 199°, which are scarcely soluble in cold alcohol. 

Dinitrodurene, C,(N O,).(CHs),, crystallizes in rhombic prisms 
and melts at 205°. 

Durenesulphonic acid, C,H(SO,H)(CH,),, is only formed with 
difficulty when durene is allowed to stand in contact with 
sulphuric acid for six to eight hours, the mixture being frequently 
stirred, while durene is liberated if the previously prepared 
sulphonic acid or its anhydrous sodium salt is treated with 
sulphuric acid. If, however, the mixture be allowed to stand 
for some days and be then heated for some hours to 40°— 50°, a 
small quantity of hexmethylbenzene, C,(CH,),,1s formed, together 
with the sulphonic acid of v-tetramethylbenzene or prehnitene 
and ®- and y-pseudocumenesulphonic acids, which are also 
obtained by heating durene with sulphuric acid : 


Durenesulphonic acid. Prehnitenesulphonic acid. 
3 3 
¢ CH; a CH, 
CH, S0,H SO,H\ /CH, 
GH, GH, 
8-Pseudocumenesulphonic acid. -Pseudocumenesulphonic acid. 
3 3 
Cr (m8 
SO,H\ /CH, \ /OEs 
GH, CH, 


The last two cannot be formed directly from pseudocumene, 
since the a-compound would in this case be the product, and 
they are therefore probably formed by the elimination of two 
different methyl gfoups from durenesulphonic acid. In the 
conversion of durenesulphonic acid into prehnitenesulphonic 
acid, a change of position of two of the side chains takes place, 
perhaps in the following way :} 


CH, <S0,H. 
\ou, CHy” CH, 

CH /?0;h> <—CH\ /EXMs 
CH, 


1 Jacobsen, Ber. Deutsch. Chem. Ges. xix. 1209. 


DURENE AND ISODURENE. 275 





It may however also be formed by the combination of methyl 
with 8-pseudocumenesulphoniec acid. 

Durenesulphonic chloride, C,H(SO,Cl)(CH,),,1s formed, together 
with the sulphonic acid, when durene is brought into ice-cold 
chorosulphonic acid, SO,(OH)Cl, and crystallizes from ether in 
brittle, vitreous prisms, which melt at 99°. 

Durenesulphamide, C,H(SO,.NH,)(CH,),, separates from al- 
coholic solution in long prisms, melting at 155°. 

Durenol, C,H(OH)(CH,),, is obtained by fusing the sulphonic 
acid with caustic potash, and crystallizes from hot alcohol in 
large, flat prisms, melting at 117°. It boils at 249° and sublimes 
very readily at its melting-point. : 

Duroquinone, C,(CH,;),0,.. Dinitrodurene is reduced by the 
action of zinc dust on its acetic acid solution to diamidodurene, 
which crystallizes in lustrous tablets and is oxidized by ferric 
chloride to the quinone; this crystallizes from petroleum-spirit 
in long, yellow needles, which melt at 111°, readily sublime and 
have a smell resembling that of quinone. It is readily reduced 
by sulphurous acid, &c., but the quinol, which is thus formed, 
rapidly re-oxidizes in the air.? 

2423 a-Tetramethylbenzene or Isodwrene (1:3:4:5) was ob- 
tained by Jannasch by the action of sodium on a mixture of 
bromomesitylene and methyl iodide.* It is also formed, to- 
gether with pentamethylbenzene and hexmethylbenzene, when 
methyl chloride is passed into a heated mixture of mesitylene 
and aluminium chloride,* and by the action of concentrated 
sulphuric acid on pentamethylbenzene.® Armstrong and Miller 
have also obtained it, accompanied by metacymene, by the 
action of zinc chloride or iodine on camphor ;® Markownikow 
detected its presence in petroleum from Baku, and Schulze in 
coal-tar.’? It is a liquid, which possesses a faint aromatic odour, 
boils at 195° ® and does not solidify in a freezing mixture. 

Bromisodurene, C,ABr(CH,),, is a liquid, which boils at 252°— 
254° and solidifies at a very low temperature to plates, which 
have a fine nacreous lustre.? 

Dibromisodurene, C,Br.(CH,),, forms needles melting at 
209°. 


1 Jacobsen and Schnapauff, Ber. Deutsch. Chem. Ges. xviii. 284. 
2 Nef, ibid, xviii. 2806 ; Ann. Chem. Pharm. ecxxxvii. 4. 


3 Ber. Deutsch. Chem. Ges. viil. 355. 4 Jacobsen, ibid. xiv. 2629. 
5 Ibid. xix. 1216. 6 Ibid. xvi. 2255. 
7 Ibid. xx. 409. 3 Ibid. xv. 1853. 


9 Bielefeldt, Ann. Chem. Pharm. cxceviii. 380. 


276 AROMATIC COMPOUNDS. 


Dinitro-isodurene, C,(NO,).(CH,),, crystallizes from hot alcohol 
in fine, transparent prisms and melts at 156°. 

If metaxylene be heated with aluminium chloride, the opera- 
tion being most advantageously conducted in a current of 
hydrochloric acid, isodurene, durene, pseudocumene, mesitylene, 
paraxylene, toluene and benzene are formed. The same pro- 
ducts are obtained from pseudocumene and mesitylene, and 
other aromatic hydrocarbons behave in a similar manner, a 
simultaneous analysis and synthesis being effected. 

Isomeric hydrocarbons are in this way apparently converted 
into one another, as, for example, metaxylene into paraxylene, 
the latter being however actually formed from toluene, which is 
also present among the products. Another instance is the 
apparent conversion of pseudocumene into mesitylene and vice 
vers 

Isodwrenol, C,H(OH)(CH,),, has been prepared from isoduridine 
and forms white crystals, melting at 80°—81°. 

Isoduridine, C, ACN H,)(CH,),, occurs among the by-products 
of the preparation of a-pseudocumidine,? and is also formed when 
the hydrochloride of the latter, or that of mesidine, is heated to 
300° with methyl alcohol? It is an oily liquid, which boils at 
250°—253°, and solidifies on cooling to crystals, which melt 
at 14°. 

Letramethylphenylearbamine, C,H(NC)(CH,),, is formed by 
the action of chloroform and alcoholic potash on the preceding 
compound. It possesses the characteristic smell of the car- 
bamines, melts at 51° and is converted into the nitril by 
heating to 240°. The latter melts at 68°—69° and is only 
attacked by hydrochloric acid at 250°, at which temperature the 
corresponding acid is not formed, its decomposition products, 
carbon dioxide and isodurene, being obtained. 

2425 v-Letramethylbenzene or Prehmitene (1:2:3: 4) was ob- 
tained by Jacobsen, who converted durene into prehnitene- 
sulphonic acid as already described, and separated this from the 
accompanying pseudocumenesulphonic acid by converting the 
mixture into the amides and recrystallizing these from alcohol. 
Pure prehnitene was obtained by heating the corresponding 
sulphamide, which is the less soluble and melts at 18°7°, with 


1 Jacobsen, Ber. Deutsch. Chem. Ges. xviii. 338 ; Anschiitz and Immendorff, 
tbid. xviii. 657 ; Anschiitz, Ann. Chem. Pharm. ecxxxy. 150. 

* Hofmann, Ber. Deutsch. Chem. Ges. xvii. 1912. 

3 Nolting and Baumann, ibid. xviii. 1147. 


TRIMETHYLBENZENECARBOXYLIC ACIDS. 277 





hydrochloric acid to 170°—180°. It is a liquid, which boils 
at 204° and solidifies at a low temperature to a macrocrystalline 
mass, melting at — 4°. 

Prehnitenesulphonic acid, accompanied by hexmethylbenzene, 
was subsequently obtained by Jacobsen as the product of the 
action of sulphuric acid upon pentamethylbenzene, C,H(CH.,),, 
and this renders it probable that in the conversion of durene into 
prehnitene, the former passes first imto pseudocumene and 
pentamethylbenzene.’ 

Dibromoprehnitene, C,Br,(CH,),, crystallizes from a mixture of 
toluene and alcohol in long prisms, melting at 210°. 

Dinitroprehnitene, C,(NO,).(CH,),, separates from alcohol in 
compact, vitreous prisms, melting at 178°. 

Friedel and Crafts, and Ador and Rilliet, have obtained a 
tetramethylbenzene by the action of methyl chloride on toluene 
in the presence of aluminium chloride, which boils at 185°—190° 
and probably consists chiefly of isodurene, while Kelbe and 
Pathe have obtained a substance by heating v-bromopseudo- 
cumene with methyl iodide and sodium, which distils at 
170°—190°* and must, according to its formation, be impure 
prehnitene. 


TRIMETHYLBENZENECARBOXYLIC ACIDS, 
C,H,(CH,),CO,H. 


The position of the carboxyl group in the following compounds 
is designated by the number 1. 

2426 Durie acid (1:2:4:5) was obtained by Jannasch, who 
named it cwmic acid, by the oxidation of durene with nitric 
acid.4 A solution of chromium trioxide in glacial acetic acid 
may also be employed as the oxidizing agent.? Reuter prepared 
it by fusing potassium a-pseudocumenesulphonate with sodium 
formate.® It is, however, best prepared by acting upon diazo- 
pseudocumene chloride with a solution of copper sulphate and 
potassium cyanide, duronitril, CgH.(CH;),CN, which crystallizes 
from alcohol in long needles, melts at 575° and boils at 

1 Ber, Deutsch. Chem. Ges, xx. 900. 

2 Ibid. xix. 1209. 3 Ibid. xix. 1551. 

4 Zeitschr. Chem. 1870, 449; Nef, Ber. Deutsch. Chem. Ges. xviii. 2801. 


5 Gissmann, Ann. Chem. Pharm. ccxvi. 205. 
6 Ber. Deutsch. Chem. Ges. xi, 29, 


278 AROMATIC COMPOUNDS. 


250°, being formed. This is converted into the acid by con- 
tinued boiling with alcoholic potash The latter is scarcely 
soluble in water, volatilizes with steam and crystallizes from 
hot benzene in needles, frequently an inch in length and having 
a splendid lustre, while it separates from alcohol in prisms, 
melting at 149°—150°. 

Dinitrodurie acid, C,(NO,).(CH,)3;CO,H, is best prepared by 
adding well-cooled solutions of potassium nitrate and duric 
acid to sulphuric acid. It forms a yellow powder, which 
is only slightly soluble in cold, more readily in hot water and 
melts at 205°. It crystallizes from dilute alcohol or alcoholic 
ether in prisms containing alcohol of crystallization, which 
is readily given off, the acid being left as an amorphous 
powder.” 

Diamidoduric acid, C(NH,),(CH,),CO,H, is formed by the 
action of zinc dust and dilute acetic acid on the preceding 
compound, It crystallizes from hot water in silky, matted 
needles, which melt at 221° with decomposition.® 

Hydroxydurie acid, C,H(OH)(CH,)3CO,H, is obtained when 
durenol is fused for a considerable time with caustic potash and 
crystallizes from dilute alcohol in small needles, melting at 148°, 
which readily sublime. Its alcoholic solution gives a fugitive 
blue colouration with ferric chloride, which produces a dirty 
brown precipitate in solutions of its salts. On heating to 
200° with hydrochloric acid, 8-pseudocumenol is formed. 

Pseudocumoquinonecarboxylic acid, C(CH,),0,(CO,H), was 
obtained by Nef by the oxidation of a solution of diamidoduric 
acid in hydrochloric acid with ferric chloride. It separates from 
an ethereal solution as an oily liquid, which after some hours 
changes into deep golden-yellow, feathery groups of needles 
which have a distinct quinone-like odour and decompose at 130° 
with evolution of gas. 

Dihydroxyduric acid or Pseudocumoquinolic acid, C(CH;),(OH), 
CO,H, is formed by the reduction of the quinone-acid in alkaline 
solution with zinc dust, and crystallizes from hot water in 
spherical aggregates of needles, which melt with decomposition 
at 210° and form a deep violet coloured solution in alkalis. 
Ferric chloride re-oxidizes it in acid solution with production of 


1 Haller, Ber. Deutsch. Chem. Ges. xviii. 93; Nef, Ann. Chem. Pharm. 
CCXXXxvVii. 3. 2 Gissmann, loc. cit. ; Nef, loc. cit. 

3 Nef, Ber. Deutsch. Chem. Ges. xviii. 3496. 

4 Jacobsen and Schnapauff, ibid, xviii. 2841. 


DURIC AND ISODURIC ACIDS. 279 


a green colouration to the quinone-acid, which forms the first 
instance of a benzoquinonecarboxylic acid. 

2427 a-Isoduric acid (1:3:4:5) was first obtaimed by 
Bielefeldt by the oxidation of isodurene,? and it was then 
shown by Jacobsen that the other isoduric acids which are 
theoretically possible are simultaneously formed by this method.* 
The mixture of acids is converted into the barium salts, that of 
a-isoduric acid being readily deposited in crystals. The acid, 
which is liberated from this, is only slightly soluble in water, and 
separates from alcohol, in which it readily dissolves, in compact 
prisms, and from ether in large, transparent, strongly refractive, 
monosymmetric crystals. It melts at 215°, readily sublimes in 
long, lustrous needles, is volatile with steam and yields hemelli- 
thene on distillation with lime. 

B-Isoduric acid (1:2:4:6) is separated from the y-acid by 
repeated recrystallization from petroleum-spirit, in which the 
latter is more readily soluble. It separates on evaporation in 
hard, lustrous, transparent prisms, which melt at 151° and yield 
pure mesitylene on distillation with lime. 

y-Lsodurie acid (1:2:3:5) crystallizes from dilute alcohol in 
needles, which melt at 84°—85° and readily volatilize with 
steam. It is scarcely soluble in cold, readily in hot water, and on 
distillation with lime yields pseudocumene. 

Prehnitic acid (1:2:3:4) is formed, unaccompanied by any 
isomeride, by boiling prehnitene with dilute nitric acid. It 
crystallizes from hot alcohol in long, transparent, vitreous prisms, 
which melt at 167°5° and volatilize tolerably readily with steam. 
On distillation with lime, it decomposes into carbon dioxide and 
hemellithene. 


DIMETHYLBENZENEDICARBOXYLIC ACIDS, 
C,H,(CH,).(CO,H),. 


2428 a-Cumidic acid (1:3:4:6). Jannasch, by the oxida- 
tion of durene, obtained duric acid and also the dibasic 
cumidic acid,® which, however, was shown by Schnapauff to be 
a mixture of two isomerides, which are also formed by the 


1 Nef, Ann. Chem. Pharm. cexxxvii. 1. 2 Tbid. excviii. 380. 
3 Ber. Deutsch. Chem. Ges. xv, 1853. 4 Jacobsen, zbid. xix. 1209. 
5 Zeitschr. Chem. 1871, 33. 


284 


280 AROMATIC COMPOUNDS. 





oxidation of duric acid with potassium permanganate and can 
readily be separated by means of their methyl ethers, 
a-Cumidic acid is also formed when dibromometaxylene is 
heated under pressure with ethyl chlorocarbonate and sodium 
amalgam. It is only slightly soluble in water, more readily in 
hot alcohol, from which it crystallizes in microscopic, vitreous 
prisms, which sublime on heating in fine plates without pre- 
viously melting. It yields metaxylene on distillation with lime. 

Methyl-a-cumidate, C,H,(CHs),(CO,.CH;),, crystallizes from 
wood-spirit in long needles, resembling asbestos, or large, thin 
tablets, melting at 76°. 

B-Cumidic acid (1:4:2:5) crystallizes from alcohol in six- 
sided prisms, which sublime in small plates and decompose into 
carbon dioxide and paraxylene on distillation with lime. 

Methyl 8-cumidate is less soluble in methyl alcohol than the 
a-compound and crystallizes in long, flat needles, which have a 
diamond lustre and melt at 114°. 

Lsocumidic acid (1:3:5:6) was obtained by Jacobsen by the 
oxidation of a mixture of 8- and y-isoduric acid. It melts at 
278°—280° and sublimes at a slightly higher temperature in 
small, transparent crystals. On heating with lime, it yields 
metaxylene.” 


BENZENETETRACARBOXYLIC ACIDS, 
C,H,(CO,H),. 


2429 Pyromellitec acid (1:2:4:5) was prepared by Erdmann 
by the distillation. of mellitic acid, C,(CO,H),, and by heating 
its salts with sulphuric acid,? and was then investigated by 
Baeyer.£ It is also formed by the oxidation of duric or cumidic 
acid with potassium permanganate (Jacobsen).° 

It is best prepared by slowly distilling a mixture of two parts 
of sodium mellitate and three parts of sulphuric acid. It 
crystallizes in asymmetric tablets, containing two molecules of 
water which are expelled at 110°, and is tolerably soluble in 
water and readily in alcohol. 

1 Ber, Deutsch. Chem. Ges. xix. 2506. 
2 Ibid. xv. 1853. 
3 Ann. Chem. Pharm. Ixxx. 281. 


4 Ibid. Suppl. vii. 85, 166, 325. 
> Ber. Deutsch. Chem. Ges. xviii, 2516. 


BENZENETETRACARBOXYLIC ACIDS. 281 





The normal salts alone have hitherto been prepared, and 
Erdmann on this account considered it as a monobasic acid of 
the formula C,HO,(C = 6, O = 8), adding that it might also be 
a dibasic acid of the formula C,H,O0,, which was doubled by 
Gerhardt for reasons which will be given under mellitic acid. 

The ethers are obtained by the action of the alcoholic iodides 
on the silver salt. 

Methyl pyromellitate, C,H,(CO,.CH,),, crystallizes in large 
plates, which are only slightly soluble in boiling alcohol and 
melt at 138°. 

Lithyl pyromellitate, C,H,(CO,.C,H,),, forms short, flat needles, 
melting at 53°, and is, like the methyl ether, volatile without 
decomposition (Baeyer), 

Dimitropyromellitic acid, C,(NO,),(CO,H),, is obtained by the 
oxidation of dinitroduric acid with potassium permanganate, and 
crystallizes in long, silky needles, which have a strongly acid 
taste.} 

Hithyl dinitropyromellitate, C,(NO,),(CO,.C,H,),, is prepared 
by the action of ethyl iodide on the silver salt; it crystallizes 
from alcohol in needles, melting at 130°. 

Hihyl diamidopyromellitate, Cy(NH,),(CO,.C,H;),, 1s formed 
when the acetic acid solution of the preceding compound is 
treated with zinc dust, and crystallizes from ether in deep fiery- 
red, lustrous prisms, which melt at 134° and volatilize without 
decomposition. 

Pyromellitic anhydride, C,)H,O,, sublimes, when the acid is 
heated, in long needles, melting at 286°, which readily dissolve 
in water, the acid being reproduced. 

Pyromellityl chloride, C,,H,O,Cl,, is formed when the acid is 
heated for some time with phosphorus chloride ; it is a crystal- 
line mass, which is gradually reconverted into pyromellitic acid 
by boiling, with water. Its constitution is undoubtedly analogous 
to that of phthalyl chloride: 

-CO /\ CO- 
OGURA aH 50. 
CCL\ /CCl, 


Hydropyromellitic acid, C,H,(CO,H), When pyromellitic 
acid is treated for some time with water and sodium amalgam, 
two isomeric compounds are formed, one of which remains 
behind on evaporation of the ethereal solution as an amorphous 


1 Nef, Ber. Deutsch. Chem. Ges. xviii. 2802 ; Ann. Chem. Pharm. ccexxxvii. 19. 


282 AROMATIC COMPOUNDS. 





mass, while isohydropyromellitic acid crystallizes in needles, con- 
taming two molecules of water, which become anhydrous at 120° 
and decompose above 200° with formation of tetrahydrophthalic 
acid. On heating with sulphuric acid, it yields pyromellitic 
acid, trimellitic acid and isophthalic acid. 

2430 Mellophanie acid (1 :2:4:6) is formed, together with the 
isomeric prehnitic and trimesic acids, when hydromellitic acid, 


C,H,(CO.H),, is heated with sulphuric acid : 


(1) C,H,(CO,H), + 380,H, = 
C,H,(CO,H), + 2CO, + 380, + 6H,0. 


(2) C,H,(CO,H), + 380,H, = 
C,H,(CO,H), + 3CO, + 380, -+ 6H,0. 


Mellophanic acid is also obtained when isoduric acid is oxidized 
with potassium permanganate.t It is readily soluble in water, 
forms an indistinct crystalline crust or short prisms and is con- 
verted into the anhydride on heating. The latter melts at 238° 
and solidifies in crystals resembling flowers of ice, which rapidly 
become indistinct and then melt at 164°. If calcium acetate 
be added to a solution of the acid, which must not be too 
dilute, and the solution heated, a flocculent precipitate is formed, 
which redissolves on cooling (Jacobsen). It is converted by 
the action of sodium amalgam and water into a hydromellophanic 
acid, which has not been fully investigated, and yields hemi- 
mellitic acid, C,H,(CO,H),, on heating with sulphuric acid. 

Prehnitic acid (1: 2:3:4) is also readily soluble in water and 
crystallizes with two molecules of water in prisms, which re- 
semble the mineral prehnite, lose their water of crystallization 
at 100° and are converted at a higher temperature into the 
anhydride, C,,H,O,. This substance melts at 239° and distils 
as a colourless oil, which solidifies in crystals resembling 
ammonium chloride. It has probably the following constitution 
(Jacobsen) : 


CO,H 


(Yo 
JO 
6O,H 


1 Jacobsen, Ber. Deutsch. Chem. Ges. xvii. 2516. 


DIHYDROXYBENZENETETRACARBOXYLIC ACIDS, 283 


The acid is converted by the action of sodium amalgam and 
water into hydroprehnitic acid, C,H,.(CO,H),, a gummy mass, 
which yields isophthalic acid and a little prehnitic acid on heating 
with sulphuric acid. 

Prehnomalie acid, C,H,(OH)(CO,H),, is formed along with 
prehnitic acid, &c., especially if the hydromellitic acid be not 
heated too long with the sulphuric acid. It crystallizes in 
needles and yields an anhydride, which melts at 210°. On heating 
with sulphuric acid or by the action of bromine and water, 
prehnomalic acid is converted into prehnitic acid. 


DIHYDROXYBENZENETETRACARBOXYLIC 
ACIDS, C,(OH),(CO,H),. 


2431 Dihydroxypyromellitic acid is obtained by the hydrolysis 
of its ethyl ether. It crystallizes from hot water in light-yellow 
prisms or separates on the addition of concentrated hydrochloric 
acid in broad, flat needles, which contain water. It gives a pure 
blue colouration with ferric chloride. 

Ethyl dihydroxypyromellitate, C,(OH),(CO,.C,H,),. The pro- 
duct of the action of pure nitric acid on ethyl diamidopyro- 
mellitate is guinonetetracarboxylic ether, C,0,(CO,.C,H,),, which 
crystallizes from alcohol in golden-yellow needles, melts at 
148°—149° and readily sublimes. It is reduced by zinc dust 
and glacial acetic acid to the ether of dihydroxypyromellitic 
acid, which crystallizes in needles, which show a blue reflection, 
melt at 126°—128° and readily dissolve in alcohol, ether, &c., 
forming solutions, which have a blue fluorescence. It is con- 
verted by the action of zinc dust and hydrochloric acid on its 
hot alcoholic solution into ethyl dihydroxydihydropyromellitate 
or ethyl diketoheamethylenetetracarboxylate, O,H,(OH),(CO,. 
C,H,), This body crystallizes in splendid, colourless needles, 
containing water, which is lost at 110°, the compound becoming 
hard and granular and melting in this state at 142°—144°. It 
shows the greatest similarity to ethyl succinosuccinate (Pt. IV. 
p. 517), is reconverted by bromine into the preceding compound, 
&e.? 


1 Baeyer, Ber. Deutsch. Chem. Ges. iv. 73 ; Ann. Chem. Pharm. celxvi, 325, 
2 Nef, ibid. cexxxvii. 19. 


284 | AROMATIC COMPOUNDS. 


The constitution of the corresponding acid is therefore ex- 
pressed by the following tautomeric formule: 





CO,H 00,H ies CO,H 
COST GH 
HO.cZ \c.0H oc’ Bee 
Het 6H \cCH—cH” 
| | 
CO,H CO,H CO,H CO,H 


THE DIMETHYLETHYLBENZENES, 


/ ous 


C.H,CCH, 
*‘\ ol 


2432 Lthylparaxylene (1:2:4), was obtained by Jacobsen by 
the action of sodium on a mixture of bromoparaxylene and 
ethyl bromide, as a liquid boiling at 185° 

s-Ethylmetaxylene (1:3: 5), is formed when methylethylketone 
is heated with sulphuric acid,? as well as by the action of sodium 
on a mixture of s-bromometaxylene and ethyl iodide It isa 
liquid, which boils at 180° and is converted by oxidation into 
mesitylenic and uvitic acids. 

s-Tribromethylmetaxylene, C,Br,(CH,),C,H,, crystallizes from 
hot alcohol in long, fine needles, melting at 218°. 

s-Trinitro-ethylmetaxylene, CO,(NO,).(CH,),C,H;, is only 
slightly soluble in hot alcohol and crystallizes in hard needles, 
melting at 238° (Jacobsen). 

a-Hthylmetaxylene (1:4:3) has been prepared from a-bromo- 
metaxylene and ethyl bromide,‘ and is also formed, together with 
dixylylethane, [(CH,),C,H,],CH.CH,, by the action of ethidene 
chloride on a mixture of metaxylene and aluminium chloride.° 
It isa liquid, which boils at 186°. 

a-Tribromethylmetaxylene, O,Br,(CH;),C,H,, crystallizes in 
small needles and melts at 90°—91° (Anschiitz and Romig). 

a-Ethylorthoxylene (1:4:2) occurs among the products of 
the action of zinc chloride or iodine on camphor; it boils at 

1 Ber, Deutsch. Chem. Ges. xix. 2515. 
2 Jacobsen, ibid. vii, 1432. 
+ Wroblewsky, Ann. Chem. Pharm. excii. 217. 


4 Fittig and Ernst, ibid. cxxxix. 192. 
> Anschiitz and Romig, ibid. ccxxxv. 322. 


THE DIMETHYLETHYLBENZENES, 285 


189°, and is converted by oxidation with dilute nitric acid into 
paraxylic acid.? 

The sulphamides of the ethylxylenes, C,H,(SO,.NH,)(CH,), 
C,H,, as deposited from absolute alcohol, are very characteristic 
compounds (Jacobsen) : 

Melting-point. 

Ethylparaxylenesulphamide, compact, transparent 


OUUREAISE: fence uent Nes cs as eater a ae ae ay 
a-Ethylmetaxylenesulphamide, vitreous prisms. . 148° 
ae Cee large, compact 

prisms 22.57 ok Ek elon Cheam oer 126° 


ACIDS, C,,H,,0, and C,,H,,03. 


2433 Methylethylsalicylic acid, C,H,.C,H,(OH)(CH,)CO,H, 
was obtained by Jacobsen by fusing the sulphonic acid of 
s-ethylmetaxylene with caustic potash. It crystallizes from 
dilute alcohol in long needles, melts at 147°—149° and gives 
a blue colouration with ferric chloride.” 

Paraxylylglyoxylic acid, (CH,),C,H,.CO.CO,H(1 : 4:2). When 
a mixture of paraxylene and acetyl chloride is acted on by 
aluminium chloride, paraxylylmethylketone, (CH,),C,H,.CO.CH,, 
is formed, as a mobile, strongly refractive liquid, which possesses 
an aromatic odour, boils at 224°—225° and is oxidized to 
paraxylylglyoxylic acid by potassium permanganate. Acids 
separate it from its salts as a thick oil, which solidifies over 
sulphuric acid to a crystalline mass, melting between 70°—80°, 
which absorbs water from the air and deliquesces, forming the 
compound (CH,),C,H,.C(OH),CO,H. It is oxidized by nitric 
acid to isoxylic acid and decomposes on distillation into the 
aldehyde of this and carbon dioxide.® 

Metaxylylglyoxylic acid, (1:3:4), is formed when metaxylyl- 
methylketone is oxidized with potassium permanganate. The 
ketone is prepared as above from metaxylene, and is a liquid, 
which smells like peppermint and boils at 227°—228°. The 
acid is an oily liquid, which solidifies over sulphuric acid toa 


1 Armstrong and Miller, Ber. Deutsch. Chem. Ges. xvi. 2255. 
2 Ann. Chem. Pharm. excv. 284. 
3 Claus and Wollner, Ber. Deutsch. Chem. Ges. xviii. 1856. 


286 AROMATIC COMPOUNDS. 





crystalline mass, melting at 85°. It is oxidized to xylic acid by 
nitric acid and yields the corresponding aldehyde on distillation.1 

Orthoxylylglyoxylic acid (1:2:4). The corresponding ketone 
is a liquid, which boils at 234° and is immediately oxidized to 
paraxylic acid by potassium permanganate.? <A cold, alkaline 
solution of permanganate converts it into orthoxylylglyoxylic 
acid, which melts at 92°. 


THE DIETHYLBENZENES, (,H,(C,H,).. 


2434 Paradiethylbenzene is formed by the action of sodium on 
a mixture of parabromethylbenzene and ethyl bromide,* as well 
as on paradibromobenzene and ethyl iodide It is a liquid, 
which boils at 178°—179° and yields ethylbenzoic and tere- 
phthalic acids on oxidation. 

Diethylbenzenes have also been obtained by passing ethyl 
chloride ® or ethylene ’ into a mixture of benzene and aluminium 
chloride, and one at least is present in petroleum from Baku 
(Markownikow). 

When ethylbenzene is heated with aluminium chloride, 
benzene, paradiethylbenzene and a little metadiethylbenzene 
are obtained, this being proved by the fact that the product, 
which boils at 176°—188°, yields terephthalic acid accompanied 
by a small amount of isophthalic acid on oxidation.® 

Diethylchlorobenzenes are formed when ethylene is passed 


into the chlorinated benzenes in the presence of aluminium 
chloride.® 


PHENYLENEDI-ACETIC ACIDS, (,H,(CH,.CO,H),. 


2435 Orthophenylenedi-acetic acid. When orthoxylylene bromide 
is Shaken up with an alcoholic solution of potassium cyanide, a 
considerable rise of temperature occurs and orthoxylylene cyanide, 


1 Claus and Strommenger, Ber. Deutsch. Chem. Ges. xix. 230, 
2 Claus and Claussen, zbid. xix. 232. 

3 Buchka and Irish, bid. xx. 1766. 

4 Fittig and Konig, Ann. Chem. Pharm. exliv. 285. 

5 Aschenbach, ibid. ecxvi. 212. 

6 Allen and Underwood, Bull. Soc. Chim. xl. 100. 

7 Balsohn, ibid. xxxi. 540. 

8 Anschiitz, Ann. Chem. Pharm. exxxv. 189. 

9 Istrati, Ann. Chim. Phys. [6] vi. 413 and 482. 


THE METHYLPROPYLBENZENES. 287 


C,H,(CH,.CN),, is obtained. It forms crystals, melting at 59°— 
60° and is decomposed into a tarry mass on heating with 
alkalis, but is converted by boiling with dilute sulphuric acid 
into orthophenylenedi-acetic acid, which crystallizes from hot 
water in fine needles, melting at 150°. 

Metaphenylenedi-acetic acid is formed by heating the corre- 
sponding cyanide with alcoholic potash and crystallizes from hot 
water in concentrically grouped needles, which melt at 170° 
and can be distilled without decomposition. The cyanide, a 
crystalline substance, which melts at 28°—29°, is prepared by 
heating metaxylylene bromide with an aqueous solution of 
potassium cyanide.’ 

Paraphenylenedi-acetie acid or Paraxylenedicarboxylic acid. The 
nitril of this acid, paraxylylene cyanide, has been prepared from 
the corresponding chloride and bromide; it crystallizes from 
alcohol in needles and from ether in long, three-sided prisms, 
melting at 98°. On heating with hydrochloric acid or alcoholic 
potash, it is converted into the acid, which crystallizes from hot 
water in long, flat needles, melts at 244° and volatilizes without 
decomposition. * 


CH 
oh: capi. 
6 ‘\ oH, 


2436 In the year 1841 Gerhardt and Cahours discovered 
cymene (cyméne), C,,H,,, together with cwminol, C,,H,,0, the 
aldehyde of cumic acid, in Roman cumin oil (Cuminum cyminum),* 
and stated that it was identical with camphene, which Dumas had 
obtained by the distillation of camphor, C,,H,,O with phos- 
phorus pentoxide, and which was then further investigated by 
Delalande.® 

Cymene was then detected in other ethereal oils, but it was: 
assumed that the hydrocarbon which occurs in nature is isomeric 
with that prepared from camphor. 

Fittig, Schiffer and Konig then obtained propyltoluene, 
C,H,.C,H,.CH;, by the action of sodium on a mixture of propyl 


THE METHYLPROPYLBENZENES, 


1 Baeyer and Pape, Ber. Deutsch. Chem. Ges. xvii. 447. 
2 Kipping, Journ. Chem, Soc. 1888, i. 41. 
3 Biedermann, Ber. Dewtsch. Chem. Ges. v. 702; Klippert, zbid. ix. 1766 ; 
Kipping, loc. cit. 
Ann. Chem. Pharm, xxxviii. 70 and 101, 5 Ibid. xxxviii. 342 and 345. 


288 AROMATIC COMPOUNDS. 





bromide and bromotoluene, which agrees in its properties with 
cymene and, like the latter, yields paratoluic acid and terephtha- 
lic acid on oxidation. They did not however consider them- 
selves justified in asserting the identity of this synthetical 
hydrocarbon with the cymene from cumin oil, 

As already mentioned, cymene occurs in association with 
cuminol; the cumic acid, which is obtained from the latter, 
decomposes on distillation with lime into carbon dioxide and 
cumene, C,H,,, which, as found by the chemists mentioned 
above, differed from propylbenzene and very probably contained 
the isopropyl group, so that cymene itself, they concluded, was 
probably isopropyltoluene.? 

Attempts to prepare the latter by the action of sodium on a 
mixture of isopropyl iodide and bromotoluene were unsuccessful, 
the iodide not being attacked. 

The products of oxidation of cymene were now investigated by 
Buliginsky and Erlenmeyer,’ and also by Dittmar and Kekulé; 
who found among them the acids already mentioned and alsoacetic 
acid, which could only be derived under these circumstances from 
anormal propyl derivative. Beilstein and Kupfer,> and Fittica,® 
then proved that natural cymene is identical with that prepared 
from camphor, and the last-named chemist prepared parapropy]l- 
toluene from pure parabromotoluene and found that it is also 
identical with the hydrocarbons in question. 

Nencki and Ziegler, on the other hand, observed that cymene, 
administered internally, appears in the urine as cumic acid,’ 
which certainly contains the isopropyl group, while Kraut found 
that cumin alcohol, prepared from cuminaldehyde, is reduced to 
cymene by heating with zinc dust® and was confirmed by Jacobsen, 
who prepared isopropyltoluene synthetically and showed that it 
differs from cymene. In order to explain the change from cumin 
alcohol into cymene “an intermolecular change of the propyl- 
group ’’® must be assumed. : 

That this actually occurs is proved by the examples already 
mentioned and those which follow. 

If the one side-chain in a derivative of para-isopropylmethyl- 
benzene, as for example, cumin alcohol or its chloride, be 


1 Ann. Chem. Pharm. exlix. 334. 
2 Hoogewerfl, ibid. exlix. 837; Jacobsen, Ber. Deutsch. Chem. Ges. xii. 429. 


3 Ann. Chem. Pharm. exl. 137. 4 Ibid, elxii. 337. 
5 Ibid. clxx. 282 and 290. 6 Tbid. elxxii. 303. 
7 Ber. Deutsch. Chem, Ges. v. 749. 8 Ann. Chem. Pharm. cxcii. 224. 


9 Ber. Deutsch. Chem. Ges. xii. 429. 


-CYMENE. © i 289 





reduced to methyl, the isopropy]l- changes into the normal 
propyl-group. 

If, on the other hand, the methyl group in cymene is oxidized 
to carboxyl, the inverse change takes place, the normal propyl- 
group being converted into the i 180-group ; in this way cymene is 
thus not only converted into cumic acid by the organism, but 
also by agitation with air and caustic soda. 

These and other observations led Widman to enunciate the 
following law: 

“When a methyl or a carboxyl group is present in a benzene 
derivative in the para-position with respect to a propyl-group, 
the latter tends to assume the normal constitution in the 
presence of the methyl, the iso-constitution in the presence of 
the carboxyl group.” ? 

2437 Cymene occurs together with cuminol in Roman cumin 
oil and in that of the seeds of Cicuta virosa,? and together with 
a terpene, C,,H,,, and thymol, C,H,.C,H,(OH)CH,, in oil of 
thyme (Thymus vulgaris) * and oil of ajowan (Ptychotis ajowan),* 
which have been used as spices and as medicine in India, Persia, 
and Egypt from very early times. It also forms a constituent of 
oil of pepper-wort (Satureja hortensis),? of oil of wild thyme 
(Thymus serpyllum),® of eucalyptus oil (Hucalyptus globulus),? 
and of essence of resin.® 

Cymene also occurs in old oil of turpentine, C,,H,,, and is 
formed from this in considerable quantity by treatment with 
sulphuric acid, which has an oxidizing action. It is formed still 
more freely, together with ether, when oil of turpentine is heated 
with ethyl sulphate.’ 

Oil of turpentine combines with bromine to form the 
dibromide, C,,H,,Br,, which decomposes on distillation,!! or 
better, by heating with aniline,” into hydrobromic acid and 
cymene. 


1 Ber. Deutsch. Chem. Ges. xix. 251, 2769, 2781. 

2 Ann. Chem. Pharm. eviii. 386. 3 Lallemand, zbid. cii. 119. 

4 Haines, Quart. Journ. Chem. Soc. viii. 289 ; Jowrn. Prakt. Chem. \xviii. 430; 
H. Miiller, Ber. Deutsch. Chem. Ges. ii. 130 ; Landolph, zbid. vi. 936. 

5 Jahns, zbid. xv. 816. 

6 Febve, Compt. Rend. xcii. 1290. 

7 Faust and Homeyer, Ber. Deutsch. Chem. Ges, vil. 1429. 

8 Ibid, xix. 1969. 

9 Riban, Bull. Soc. Chim. xix. 242; xx. 101; xxi. 4; Wright, Journ. Chem. 
Soc. 1873, 700; Chem. News, xxix. 41; Richter and Orlowsky, Ber, Deutsch. 
Chem. Ges. vi. 1257 ; Tilden, Jowrn. Chem. Soc. 1878, i. 80. 

10 Bruere, Compt. Rend. xc. 1428. 

11 Barbier, Ber. Deutsch. Chem. Ges. v. 215. 

12 Oppenheim, ibid. v. 94 and 628. 


290 AROMATIC COMPOUNDS. 


Jodine exerts a very violent action upon oil of turpentine, so 
that even ignition can occur when large amounts are added. If 
it be carefully added in small quantities and the solution heated 
for some time, cymene is formed according to the following 
equation :? 


C,Hig + 1, = Cy Hy + 2H1. 


Several of the isomerides of oil of turpentine behave in the 
same manner, readily losing two atoms of hydrogen and passing 
into cymene. 

Camphor, C,,H,,0, is also readily converted into cymene by 
elimination of water, which may be effected by heating with 
phosphorus pentoxide, phosphorus pentachloride or phosphorus 
pentasulphide. 

In order to prepare cymene, camphor is distilled with phos- 
phorus pentasulphide : ? 


5C,,H,,O + PS, = 5C,,H,, + 5H,8 + P,0;. 


The product is purified by washing with caustic potash and 
rectification. 

A better yield is obtamed by mixing equal molecules of 
camphor and phosphorus pentoxide, heating gently until the 
reaction commences, when the flame must be removed, and 
pouring off the cymene from the metaphosphoric acid. It is 
then heated once more with phosphorus pentoxide and distilled 
two or three times over sodium.? 

It may be prepared from oil of turpentine by adding 4 per 
cent. of phosphorus trichloride and passing in one molecule of 
chlorine for every molecule of the hydrocarbon present, the 
temperature being kept at 25° and not being allowed to rise 
above this point; the product is then washed with water, dried 
and distilled over sodium.* 

Cymene is a strongly refractive, aromatic smelling liquid, 
which boils at 175° and has the sp. gr. 0°791 at 0°. It gives a 
characteristic absorption spectrum by means of which it can be 
detected in essential oils.® 

It combines with aluminium bromide to form the compound 
3C,,H,,+Al,Br,, a reddish brown, transparent liquid, which 


1 Kekulé, Ber. Deutsch. Chem. Ges. vi. 487. 
2 Pott, dbid. ii, 121. 

3 Fittica, Ann. Chem. Pharm. clxxii. 307. 
4 Naudin, Bull. Soc. Chim. xxxvii. 111. 

> Hartley, Jowrn. Chem. Soc. 1880, i. 676. 


CYMENE COMPOUNDS. 291 





reacts very energetically with bromine, pentabromotoluene and 
isopropyl bromide being formed, which are therefore also formed 
when bromine is gradually added to cymene containing a little 
aluminium, the compound just described being continuously 
formed and decomposed.! 

It forms a similar compound with aluminium chloride 
(Gustavson), and on heating with the chloride decomposes 
with formation of toluene and high boiling condensation 
products.” 

2438 Addition products of cymene. Oil of turpentine and its 
isomerides, which are converted into cymene by the loss of two 
hydrogen atoms, must be considered as dihydrocymenes. They 
will however be subsequently described. 

Hexhydrocymene, C,y)H, occurs in essence of resin and boils 
at 171°—173° (Renard). 

Halogen substitution products of cymene. When chlorine is 
passed into boiling cymene, cymyl chloride, C,H,.C,H,.CH,Cl, is 
formed, together with two isomeric compounds, one of which is 
unattacked by alcoholic potash, while the other, C,H,Cl.C,H,.CH,, 
is converted by it into allyltoluene,? C,H,.C,H,.CH,. 

Orthochlorocymene, C,H,.C,H,Cl.CH,(CH, : Cl: C,H, = 1:2: 4), 
was first prepared by Kekulé and Fleischer from carvacrol, 
C,H,.C,H,(OH)CH,, by the action of phosphorus pentachloride,* 
and has also been obtained by Gerichten by the action of chlorine 
on cymene in the presence of iodine.’ It is an almost odourless, 
colourless liquid, which boils at 208°—211° and is converted 
into metachloroparatoluic acid by oxidation. 

Metachlorocymene (1 : 3: 4)is formed by the action of phos- 
phorus chloride on thymol, and is a liquid which boils at 
213°—214° and is oxidized by nitric acid to a mixture of chloro- 
cumic, orthochloroparatoluic and chloroterephthalic acids.® 

Orthobromocymene, C,H,.C,H,Br.CH,, is obtained when bro- 
mine is allowed to act upon cymene in the presence of iodine, 
and is a liquid which smells like cymene, boils at 228°—229°, 
and yields a-bromoparatoluic acid on oxidation. 

Metabromocymene is formed, together with thymyl phosphate, 


1 Gustavson, Bull. Soc. Imp. Nat. de Moskow, 1836, Nr. 2. 

2 Anschiitz, Ann. Chem. Pharm. cexxxv. 191. 

8 Errera, Gaz. Chim. Ital. xiv. 283. 

4 Ber. Deutsch. Chem. Ges. vi. 1090. 

5 Ibid. x. 1249. 

6 Carstanjen, Journ. Prakt. Chem. [2], iii. 63 ; Gerichten, Ber. Deutsch. Chem. 
Ges. xi. 364; Fileti and Crosa, ibid. xx. Ref. 139. 

7 Landolph, ibid. v. 267 ; see also Fittica, Ann. Chem. Pharm. clxxii. 310. 


292 AROMATIC COMPOUNDS. 


when thymol is heated with phosphorus pentabromide (Fileti 
and Crosa) : 


4, C, )H,,.0H + PBr, = C,,H,,Br + PO(OC,,H,s); + 4HBr. 


Its sulphonic acid is formed by the action of bromine on cymene- 
orthosulphonic acid. When this is heated with steam in pre- 
sence of sulphuric acid, metabromocymene is obtained as a 
liquid boiling at 232°—233° (Fileti and Crosa). 

Cymene-orthosulphonic acid, C,H,.C,H,(S0,H)CH,. Cahours 
and Gerhardt, as well as Delalande, obtained a sulphonic acid 
by the action of fuming sulphuric acid on cymene, which was 
then investigated by Sieveking,? Beilstein and Kupffer? and 
Jacobsen. Further investigations then proved that a small 
quantity of an isomeric acid is also formed.°® 

The orthosulphonic acid is the chief product and crystallizes 
from dilute sulphuric acid in tablets containing two molecules 
of water. On fusion with potash it is converted into carvacrol. 

Cymenemetasulphonic acid can readily be separated from the 
ortho-acid by means of the barium salt, since that of the latter 
crystallizes in plates, which are only slightly soluble in water 
and have a harsh, bitter taste, while that of the meta-acid is 
extremely soluble and remains on evaporation as a sweet gela- 
tinous mass. The free acid, obtained from the lead salt, which 
possesses very similar properties, separates from a very concen- 
trated, syrupy solution in crystalline granules. 

Nitrocymene, C,H,.C,H,(NO,)CH,;, was obtained by Barlow 
by the action of well-cooled, fuming nitric acid on cymene.® 
According to Landolph’? and Fittica,® it is better to employ 
nitric acid of sp. gr. 1°4, heated to 50°. It is a yellowish, faintly 
odorous liquid, which is volatile with steam and is converted 
into @-nitroparatoluic acid by oxidation. The product of oxi- 
dation, according to Widman and Bladin, consists chiefly of 
paratolylmethylketone (p. 145),° in the formation of which 
the normal propyl group must have passed into the isopropyl 
form. 


* Kelbe and Koschnitzky, Ber. Deutsch. Chem, Ges. xix. 1730. 

2 Ann. Chen. Pharm, evi. 257. 

3 Ibid. clxx. 287. 

4 Ber. Deutsch. Chem. Ges. xi. 1058. 

5 Claus and Cratz, ibid. xiii, 901; Spica, ibid. xiv. 653; Claus, ibid. X1v. 
2139. 

6 Ann. Chem. Pharm. xev. 245. ° 7 Ber. Deutsch. Chem. Ges. vi. 937. 

8 Ann. Chem. Pharm. elxxii. 314, 9 Ber. Deutsch. Chem. Ges. xix. 584. 


THYMYLAMINE. 293 





Another substance is also formed, which crystallizes in needles 
or small plates, melts at 125° and is not volatile with steam, 
which was considered to be an isomeric nitrocymene, until 
Gerichten showed that this is not the case, since it is converted 
into paratoluic acid by heating with sulphuric acid or caustic 
potash solution.1 According to Holleman, this body is the 
isonitroso-compound of a diketone and has the following con- 
stitution :? 


CH,.C,H,.CO.C(NOH)C(NOH)CO.C,H,.CH,. 


Metamidocymene or Thymylamine, C,H,.C,H,(NH,)CH,, was 
obtained by Widman by converting nitrocuminaldehyde, C,H,. 
C,H,(NO,)CHO, into nitrocumidenechloride by the action of 
phosphorus chloride, and reducing this with zine and hydro- 
chloric acid : 


HCl, es 
C,H, + 10H = O,H,, + 2H,O + 2HCL 
\No, \NH, 


It is also formed, together with dithymylamine, when thymol or 
metacymophenol is heated to 350°—360° with zinc bromide 
ammonia and ammonium bromide.* It is an oily, unpleasant 
smelling liquid, which boils at 230°; its salts colour pine-wood 
yellow. 

Dithymylamine, (C,H,.C,H,.CH,),NH, is an oily liquid 
which has a pleasant aromatic odour, and boils at 340°—345°. 

Orthamidocymene or Carvacrylamine was prepared by Lloyd 
from orthocymophenol or carvacrol as an oily liquid, which has 
a not unpleasant odour and boils at 241°—242°, It is probably 
identical with the cymidine, which Barlow obtained by the 
reduction of nitrocymene and described as a yellowish oil, boiling 
at 250°, the hydrochloride of which colours pine-wood yellow. 

Dicarvacrylamine is an extremely pleasant smelling oil, which 
boils at 344°—348° (Lloyd). 

Azocymene, (C,H,.C,H,.CH,),.N,, was obtained by Schumow 
by diluting cymene with 3 parts of glacial acetic acid, cooling 
the mixture with ice and salt, carefully adding concentrated 
nitric acid and pouring the product into water. The precipi- 
tated nitrocymene, which is not described, is then converted 


1 Ber. Deutsch. Chem. Ges. xi. 1092. 2 Ibid. xx. Ref. 873. 
3 Ibid. xv. 166. 4 Rachel Lloyd, cbid. xx. 1254. 


294 AROMATIC COMPOUNDS. 





into azocymene by reduction with sodium amalgam. It crys- 
tallizes from benzene in ruby-red, rhombic tablets, melting 
at 86° 

2439 Metacymophenol or Thymol, C,H,.C,H,(0H)CH;, Neu- 
mann, court apothecary in Berlin, observed in 1719 that 
crystals, which he thought were camphor, are deposited from _ 
oil of thyme, but Brown explained that these had long been 
known in England under the name of Sal volatile thyma, and are 
different from camphor. This compound was more fully investi- 
gated by Lallemand and named thymol.? It also occurs, as pre- 
viously mentioned, in Ajowan oil, and was investigated by 
Haines? and Stenhouse.* It has long been known in India, as 
in the preparation of the oil it separates from the aqueous 
distillate in crystals and is sold in the bazaars under the name 
of Ajwain-ka-phyl or flowers of Ajowan.® It was also obtained 
from essential oil of monarda (Monarda punctata) by Arppe, and 
was identified as thymol by Stenhouse and Gerhardt.® 
_ It is prepared from oil of thyme or oil of Ajowan, from which 
it can be obtained by fractional distillation. It is however 
more usual to extract it by agitation with caustic soda solution 
and precipitate it from the solution by hydrochloric acid. It is 
then purified by recrystallization from alcohol, or better, glacial 
acetic acid. 

It forms large monosymmetric or asymmetric crystals, which 
smell like thyme, have a sharp, burning taste, and melt at 50°.” 
According to Lallemand it boils at 230°, while Stenhouse states 
the boiling point as 222°, On distillation with phosphorus 
pentasulphide it yields cymene (Fittica), and is decomposed 
into metacresol and propylene by heating with phosphorus 
pentoxide.® 

It yields a violet-red colouring matter, C,,H.,N,O,, on treat- 
ment with sulphuric acid and nitrous acid (Liebermann, sce 
Pt. I. p. 176). Owing to its strong antiseptic properties it 
is employed in medicine, since it has a more powerful action 
than phenol and is at the same time less corrosive and poisonous. 


1 Ber. Deutsch. Chem. Ges. xx. 8, 218. 

2 Compt. Rend. xxxvii. 498 ; xxxvili. 1022; xliii. 857; Ann. Chem. Pharm. 
L122 cis 10. 

3 Quart. Journ. Chem. Soc. viii. 289. 

* Ann. Chem. Pharm. xciii. 269 ; xcviii. 307. 

° Haines; Stenhouse ; Pharmacographia, 2nd Edit. 308. 

6 Trait. Chim. Org. iii. 610. 

7 Menschutkin, Beilstein’s Organ. Chem. 1048. 

8 Engelhardt and Latschinow, Zeitschr. Chem. 1869, 621. 


THYMOL. 295 


* 





As a phenol it forms salts, ethers, and ethereal salts : 


Melting- Boiling- 


oint. oint. 
Thymyl methyl ether! C,,H,,OCH, .. . pea 3167° 
Thymyl ethyl ether? C,,H,,OC He. 2 222° 
Thymyl ethenyl ether,® ake EC aeeao -— 
Thymyl BHOE DEAS. (CG Hyajeh Oe erat tol ODF _ 
Ehyrtiy) silicate,®. (CH) SiO pita wee 43° 450° 
Thymyl ethyl carbonate,® C,,H,3(C, H,)CO, — 259°—262° 
Dithymyl! carbonate, (C,,H,;),CO;. . . . 48° — 
Thymyl acetate,’ C,,H,,0C;H,0 .... — 244:7° 


Thymyl benzoate,® C,,H,,0C,H,O . . . . 32° 


Thiothymol, C,H,.C,H,(SH)CH,, is formed, together with 
cymene, by the action of phosphorus pentasulphide on thymol, 
and is a liquid which has a characteristic pungent odour and 
boils at 230°—231°, It readily combines with mercuric oxide 
to form the mercaptide, (C,,H,,S),Hg, which separates from 
alcohol in greenish, rhombohedral forms.° 

2440 Orthocymophenol (1:2:4). Schweizer discovered that 
cumin oil contains in addition to carvene, CLs, an oxygenous 
compound, which is converted when the oil is distilled with 
potassium, caustic potash, iodine or glacial phosphoric acid, into 
carvacrol, a thick, oily liquid, which has a persistent, pungent 
taste and a characteristic, unpleasant odour, its vapour attacking 
the lungs very violently. 

Claus obtained an oily liquid, accompanied by other products, 
by the distillation of camphor with iodine, which resembles 
creosote in both taste and smell, and was therefore named by him 
camphor creosote+ Schweizer then repeated this research and con- 
vinced himself that carvacrol and camphor creosote are identical.” 

The oxygenated constituent of cumin oil was first isolated by 
Volckel, who named it carvol, and gave it the formula C,,H,,0., 
assigning to carvacrol the formula C,,H,,O,(C =6; O=8).#* 

1 Paternd, Bull. Soc. Chim. xxv. 32. 

2 Jungfleisch, Zeitschr. Chem. 1865, 532. 

3 Paterno. 

4 Engelbardt and Latschinow, Zectschr. Chem. 1869, 44. 
5 Hertkorn, Ber. Deutsch. Chem. Ges. xviii. 1693. 

6 Richter, Jowrn. Prakt. Chem. [2], xxvii. 503. 

7 Paterno. 

8 Stohmann, Journ. Prakt. Chem. [2], xxxvi. 7. 

9 Fittica, Ann. Chem. Pharm. elxxii. 325. 

10 Journ. Prakt. Chem. xxiv. 271. 


11 [bid. xxv. 266. 12 Tbid. xxvi. 118. 
1 Ann. Chem. Pharm. lxxxv. 246. 


285 


296 AROMATIC COMPOUNDS. 





Varrentrapp subsequently showed that carvol has the composi- 
tion C,,H,,0., and Gerhardt then suggested that it 1s isomeric 
with carvacrol.! 

Pott 2and Hugo Miiller® obtained an oxycymol or cymophenol 
by fusing cymenesulphonic acid with caustic potash, and this 
was shown by Kekulé and Fleischer to be also identical with 
carvacrol and camphor creosote.* 

The same substance occurs in smaller quantity in Thymus 
serpyllum, accompanied by thymol and cymene. It forms 
about 30 per cent. of oil of pepper-wort (Satureja hortensis 
et montana) and from. 50—80 per cent. of Spanish oil of hops or 
Cretan oil of marjoram (Origanum hirsutum et creticum), from 
which it can be readily separated.2 A good yield is also 
obtained by fusing sodium cymenesulphonate with three parts of 
caustic potash.® | 

Its formation from the isomeric carvol, which will be sub- 
sequently described, is especially worthy of note. The con- 
stitution of these compounds is expressed by the following 
formulae : 


Carvol. Carvacrol. 
CH, CH, 
| | 
CH. C 

NS Via 

HC. .CO HC C.OH 
| Peak nat 
HO. aCH. HC CH 

Ng \Z 
C C 
| | 
C,H, C3H, 


The latter, therefore, stands in the same relation to the 
former as phoroglucinol to triketohexhydrobenzene, which, how- 
ever, is not known in the free state (Pt. IV. p. 518). 

When carvol is heated with metaphosphoric acid or crystallized 
phosphoric acid, it is converted into carvacrol, so much heat 
being evolved that an explosion may occur; it is therefore 


1 Trait. Chim. Organ. iii. 615. 

2 Ber. Deutsch. Chem. Ges. ii. 121. 

3 Ibid. ii. 180. 

4 Ibid. vi. 1087. 

5 Jahns, ibid. xv. 816; Huller, Compt. Rend. xciv. 132. 
6 Jacobsen, Ber, Deutsch. Chem. Ges. xi. 1060. 


ORTHOCYMOPHENOL OR CARVOL. 297 








better to employ crude cumin oil and subsequently separate 
the carvacrol from the carvene by means of caustic potash 
solution (Kekulé and Fleischer). 

According to Lustig, the action is not so violent and it is most 
advantageous to heat a mixture of 50 grms. of carvol and 
50 grms. of cumin oil with 12 grms. of glacial phosphoric acid 
to boiling for 3—4 hours, pour off the thick liquid and isolate 
the carvacrol by fractional distillation. 

Properties—It is a somewhat viscid liquid, which, according 
to Miiller, has an aromatic odour, resembling that of Russian 
leather, while Jacobsen states that it has a faint, characteristic 
odour, which becomes pungent when the liquid is heated. It 
boils at 237° and solidifies on cooling to crystals, which melt at 
about 1°. Its alcoholic solution is coloured green by ferric 
chloride (Jahns). On distillation with phosphorus penta- 
sulphide, it yields cymene and is decomposed by heating with 
phosphorus pentoxide into propylene and a cresol (Kekulé and 
Fleischer), which is the ortho-compound, while on heating with 
phosphorus oxychloride it is converted into cymophenyl phosphate, 
(C,,H,3)3PO,, which crystallizes from benzene in prisms or 
tablets and melts at 75° (Kreysler). 

Boiling-point, 
Cymophenyl methyl ether,? C,,H,,OCH, . .  216°8° 
Cymopheny] ethyl ether,® C,,H,,0C,H,. . . 235° 
Cymopheny] acetate, C,,H,,0.C,H,0 .. . 245°8° 


Thiocymene or Thiocarvacrol, C,H,.C;H,(SH)CH,, is obtained 
in a similar manner to thiothymol and is also formed, together 
with cymene, by the distillation of carvol or camphor with 
phosphorus pentasulphide and by the action of nascent hydrogen 
on cymenesulphonic chloride.* It is a liquid, which has a 
characteristic aromatic odour, boils at 235°—236° and forms a 
mercaptide, (C,,H,,8),Hg, which crystallizes from alcohol in 
stellate groups of needles.® 

2441 Thymoquinone, C,H,.C,H,0,.CHs, was first obtained by 
Lallemand by the oxidation of thymol with sulphuric acid and 
manganese dioxide and termed thymoil.® It may be prepared in 


1 Ber. Deutsch. Chem. Ges. xix. 11. 2 Pisati and Paternd, zbid. viii. 71. 

3 Lustig, loc. cit. 

4 Flesch, ibid. vi. 478; Rodenberg, cbid. vi. 669; Fleischer and Kekulé, 
loc. cit. 

5 Fittica, Ann. Chem. Pharm. clxxii. 325. 

6 Ibid. cii. 119. 


298 AROMATIC COMPOUNDS. 


a similar manner from carvacrol,! its formation being explained 
by the following constitutional formula : 


CH, 
| 
GC 
o> 
eh 


H O 


bet 
OC CH 
ESA 
C 


| 
C3H, 


It is only slightly soluble in water, readily in alcohol, and 
crystallizes in lustrous, yellow tablets, which have a penetrating 
aromatic odour, melts at 45°5°, boils at 232°, and is readily 
volatile with steam.’ 

If its ethereal solution be allowed to stand in the light, it is 
converted into polythymoquinone, which crystallizes in long, light 
yellow, odourless needles, which melt at 200°—201° and sublime 
at a higher temperature, but do not volatilize with steam. It is 
not reduced by sulphurous acid but is converted into thymo- 
quinol by boiling with hydriodic acid and red phosphorus, by 
heating the alcoholic solution with zine and hydrochloric acid 
or by distillation over zinc dust.® 

Thymoquinol, C,H,.C,H,(OH),CH,, which was called thy- 
motlol by Lallemand, is formed by the reduction of the quinone 
with sulphurous acid. It crystallizes from hot water in four- 
sided, colourless, lustrous prisms, melting at 139°5°. 

Dimethylthymoquinol, C,H,.C;H,(OCH,),CH,, forms the chief 
constituent of the ethereal oil of Arnica root (p. 5). It boils at 
about 235°, 1s resolved into methyl iodide and thymoquinol by 
heating with hydriodic acid.* 

Lhymoquinhydrone, C,H,.C,H,(OH),CH3 + C,H,.C,H,0,.CH,, 
is formed by the combination of the quinone with the quinol, 
and crystallizes in lustrous black needles. | 

Thymoquinone contains two hydrogen atoms, a and £, of 


1 Kekulé and Fleischer, Ber. Deutsch. Chem. Ges. vi. 1087. 

2 Carstanjen, Journ. Prakt. Chem. [2], iii. 54 

* Liebermann, Ber, Deutsch. Chem. Ges. x. 2177; Liebermann. and Hinski,’ 
tbid. xviii. 3193. 

4 Sigel, Ann. Chem. Pharm. clxx. 368. 


THYMOQUINONE. 299 


unequal value and therefore gives rise to two series of mono- 


substitution products. 
CO 


a-Chlorothymoquinone, C,)H,,ClO,. When thymoquinone is 
brought into hydrochloric acid saturated at 0°, a-chlorothymo- 
quinone, C,,H,,Cl0,, is formed; it crystallizes from petroleum- 
ether in silky needles, melting at 70°} and is oxidized by 
distillation with ferric chloride to the quinone. The latter 
is a yellow liquid, which cannot be distilled without decomposi- 
tion, but is volatile with steam. 

8-Chlorothymoquinone is formed by the action of chlorine on 
the corresponding bromine compound and is also an oily liquid, 
The corresponding quinol resembles it closely in appearance. 

8-Bromothymoquinone, C,,H,,BrO,. Thymoquinone is not 
converted into the a-bromoquinol by solution in hydrobromic 
acid, but the ®-compound is formed. This crystallizes in 
colourless needles, melting at 53°, while the corresponding 
quinone forms lustrous yellow plates, melting at 45°. 

a-Chloro-8-bromothymoquinone, C,,H,,ClBrO,, is formed by 
the careful bromination of the a-chloroquinone and crystallizes 
from hot alcohol in small, yellow plates, which melt at 87°. It 
is not affected by sulphurous acid, but is reduced by free 
hydroxylamine to the quinol, which is also formed by the action of 
hydrochloric acid on the 8-bromoquinone and of hydrobromic acid 
on the a-chloroquinone ; it crystallizes in needles, melting at 63°. 

8-Chloro-a-bromothymoquinone has been prepared from the 
§8-chloroquinone and forms reddish yellow plates, melting at 78°, 
while its quinol crystallizes in needles, which melt at 56° 

2442 Hydroxythymoquinone, C,,H,,(OH)O,. Thymoquinone 
reacts with dimethylamine in alcoholic solution in the following 
manner : 


2C,,H,,0, + NH(CH;), = C,,H,.(OH), + C,,H,,0,N(CH,),. 
Dimethylamidothymoquinone is precipitated from this solution 


by water in violet-black, oily drops, and is converted by heating 
1 Schniter, Ber. Deutsch. Chem. Ges. xx. 1316, 


300 AROMATIC COMPOUNDS. 


with hydrochloric acid into hydroxythymoquinone. This sub- 
stance crystallizes from hot water in yellow needles or small 
plates, which melt at 166°—167° 

Diamidothymoquinone, C,)H,,(NH,).0, If the hydroxy- 
quinone be boiled with aniline and alcohol, hydroxythymoquinone- 
anilide, C,,H,,(OH)O,NH(C,H;), is formed and crystallizes in 
dark violet needles, which have a metallic lustre and melt at 
134°—135°. On heating with saturated alcoholic ammonia, it 
is converted into diamidothymoquinone, which crystallizes in 
blue-black needles with a metallic lustre and sublimes on 
heating without previously melting.’ 

Thymoquinonoxime or Nitrosothymol, O,H,.C,H,O(NOH)CH,, 
is formed when a solution of thymol in caustic potash is treated 
with potassium nitrite and sulphuric acid? It may also be 
obtained by the combination of hydroxylamine with thymo- 
quinone.* It is slightly soluble in water, readily in alcohol, and 
crystallizes from chloroform in small, yellow needles, which melt 
at 160°. Its alkali salts crystallize in long, dark yellow needles. 
It is oxidized by potassium ferricyanide in alkaline solution to 
nitrothymol, C,H,C,H,(OH)(NO,)CH,, and this is also formed 
when an aqueous solution of thymosulphonic acid is heated with 
nitric acid.® It crystallizes in thin, yellow needles, which show 
a bluish fluorescence and melt at 140°. 

Nitrosothymol is reduced by the action of tim and hydro- 
chloric acid to amidothymol, C,H,.C,H,(OH)(NH,)CH,, which is 
very unstable in the free state and is converted by bromine,® 
ferric chloride,’ or chromic acid® into thymoquinone, while 
bleaching powder acts upon it in hydrochloric acid solution with 
production of thymoquinone chlorimide, C,H,.C,H,O(NOCI)CH,, 
a yellow liquid, which possesses a penetrating odour and decom- 
poses on heating, but is volatile with steam (Andresen). 

Polythymoquinonoxime, [C,H;.C,H,O(NOH)CH,],, is formed 
by the combination of polythymoquinone with hydroxylamine 
and forms a crystalline powder, which detonates when rapidly 
heated and is reduced to amidothymol by tin and hydrochloric 
acid. 


1 Schulz, Ber. Deutsch. Chem. Ges. xvi. 898. 

2 Anschiitz and Leather, Ann. Chem. Pharm. ecxxxvii. 114. 
3 R. Schiff, Ber. Deutsch. Chem. Ges. viii. 1500. 

* Goldschmidt and Schmid, bid. xvii. 2060. 

5 Liebermann, ibid. x. 612. 

§ Andresen, Journ. Prakt. Chem. [2], xxiii. 172. 

? Armstrong, Ber. Deutsch. Chem. Ges. x. 297. 

8 Liebermann and Ilinski, <béd. xviii. 3198. 


_ PARA-ISOCYMENE. . 301 


Polythymoquinonedioxime, [C,H,.C,H,(NOH),CH;,],is obtained, 
when the polyquinone is heated with hydroxylamine, as a diffi- 
cultly soluble, white powder, which is converted by reduction 
into diamidocymene hydrochloride, C,H,.C,H,(NH,),CH,(C1H),. 
This salt crystallizes in needles, which readily decompose with 
formation of ammonium chloride and are oxidized to thymo- 
quinone by ferric chloride (Liebermann and Ilinski). 

Nitrosocarvacrol has been prepared from carvacrol and crystal- 
lizes in yellowish prisms, melting at 153°. It is converted by 
oxidation into nitrocarvacrol, which forms yellowish needles, 
melting at 77°—78° and yields amidocarvacrol, which is likewise 
very unstable in the free state, on reduction. 

2443 Orthopropylmethylbenzene or Orthocymene,C,H,.C,H, CHs, 
is obtained by the action of sodium on a mixture of orthobromo- 
toluene and propyl iodide. It is an aromatic smelling liquid, 
which boils at 181°—182°? and behaves towards potassium per- 
manganate in the cold in the same manner as orthomethylethyl- 
benzene, the phthalic acid produced being accompanied by a 
considerable amount of terephthalic acid (p. 144). 

Metapropylmethylbenzene or Metacymene has been prepared in 
a similar manner from metabromotoluene ; it boils at 176°— 
177°5°.° Like the ortho-compound, it yields two sulphonic acids 
with sulphuric acid. 

Para-isocymene, (CH,),CH.C,H,.CH,, was obtained by Jacobsen 
by heating parabromocumene and methyl iodide with sodium in 
the presence of ether and a few drops of acetic ether, without 
which the reaction only proceeds very slowly. 

It is a liquid, which has a similar smell to cymene, does not 
solidify at —20°, boils at 171°—172°, and has a sp. gr. of 0°8702 
at 0°. On heating to 90°—100° with sulphuric acid, two sulphonic 
acids are obtained: the one which is formed in preponderating 
amount, yields a barium salt, (C,,H,,5O0,),Ba + H,O, which 
crystallizes in hair-like needles and is more than twice as soluble 
in water as barium cymenesulphonate. The barium salt of the 
other acid forms an opaque, readily soluble, semi-crystalline mass.* 

Meta-isocymene, (CH,),CHC,H,.CH,, occurs in resin spirit, 
and among the products formed by the action of zinc chloride ® 


1 Paternd and Canzoneri, Ber. Deutsch. Chem. Gres. xii. 383. 

2 Claus and Hansen, zbid. xiii. 867. 3 Claus and Stiisser, 7bzd. xiii, 899. 
4 Ibid. xii. 429. 

5 Kelbe, Ann. Chem. Pharm. cecx. 13 Renard, Ann. Chim. Phys. [6], i. 249. 

6 Armstrong and Miller, Ber. Deutsch. Chem. Ges. xvi. 2255. 


302 AROMATIC COMPOUNDS. 





or phosphorus pentoxide! on camphor, and is formed when 
toluene is heated with isopropyl iodide and aluminium chloride 
(Kelbe). It is a strongly refractive liquid, which boils at 174°— 
176° and smells like cymene. It is oxidized by dilute nitric 
acid to metatoluic acid, and by chromic acid or potassium per- 
manganate to isophthalic acid. It 1s violently attacked by 
chlorine and bromine, but substitution only takes place in the 
side chains, even in the cold. 

a-Bromometa-tisocymene, (CH,),CH.C,H,BrCH,(1 : 4: 3), 1s 
formed when a solution of hydrobromic acid is mixed with one 
of a-meta-isocymenesulphonie acid. It is a strongly refractive 
liquid, which smells somewhat like roses and boils at 225° (Kelbe 
and Czarnowski.) It is oxidized to a-bromometatoluic acid by 
nitric acid. 

8-Bromometa-isocymene (1:6:3). In the preparation of the 
preceding compound, a bromosulphonic acid is simultaneously 
formed, which yields the A-substitution compound on heating 
with concentrated hydrochloric acid. This substance has a faint 
aromatic odour, boils at 224°, and is slowly oxidized to 8-bromo- 
metatoluic acid by nitric acid. 

On further oxidation, both these bromometa-isocymenes yield 
bromisophthalic acid, melting at 283°? 

Dibromometa-isocymene, (CH,),CH.C,H,Br,.CH, (1 : 4: 6:3), 
is formed by heating the solution of the sulphonic acid with 
bromine, and is a liquid, which has a faint odour and boils at 
272°— 273°. 

Meta-rsocymenesulphonie acid, (CH,),CH.C,H,(SO,H)CH,, is 
obtained by dissolving the hydrocarbon in hot sulphuric acid in 
two modifications, which may be separated by means of their 
barium salts. That of the a-acid, which is the chief product, 
crystallizes with one molecule of water in large, nacreous plates, 
which are only slightly soluble in water, while the salt of 
the @-acid is readily soluble and contains eight molecules of 
water. 

Meta-isocymophenol or Cymenol, (CH,),CH.C,H,(OH)CHg, has 
been prepared from the a-sulphonic acid; it is a strongly 
refractive liquid, which boils at 231°, and has an odour re- 
sembling thymol and simultaneously wood smoke, and a vapour 

which causes violent coughing. Its aqueous solution is coloured 


1 Spica, Gaz. Chim. Ital. xii. 487, 548. 
2 Kelbe, Ber. Deutsch. Chem. Ges. xv. 89. 
3 Kelbe and Czarnowski, Ann. Chem. Pharm. ccxxxyv. 27, 


CYMYL COMPOUNDS. 303 


a faint violet by ferric chloride. On fusion with caustic potash 
it yields a-hydroxyisophthalic acid and para-isopropylphenolcar- 
boxylic acid (p. 310), its constitution being thus determined. 

Cymenyl methyl ether, C;H,(CH3)C,H,.0CH,, is an oily liquid, 
which has an aromatic odour and a burning taste and boils 
at 217° 

Cymenyl benzoate, C,H,(CH,)C,H,.0.CO.C,H,, crystallizes 
from petroleum-spirit in monosymmetric prisms, melting at 73° 
(Kelbe). 

Nitrometa-isocymene, (CH,),CH.C,H,(NO,)CH;, is an oily 
liquid, which has a spicy odour and yields nitrotoluic acid, 
melting at 214°, on oxidation. 

Amidometa-isocymene or Meta-isocymidine, (CH,),CH.C,H, 
(NH,)CH,, is a strongly refractive liquid, which has an odour. 
resembling that of aniline and boils at 232°—233°? 


CYMYL-COMPOUNDS. 


2444 Cymyl alcohol or Cumin alcohol, (CH,),CH.C,H,.CH,OH, 
was obtained by Kraut by the action of alcoholic potash on 
cuminaldehyde. It is an oily, faintly aromatic smelling liquid, 
which has a burning taste, boils at 246°6°, and has a sp. gr. of 
09775 at 15°. It is reduced to cymene by continued boiling 
with zinc dust (p. 288).° 

Cymyl chloride, (CH,),CH.C,H,.CH,Cl, is formed by the 
action of hydrochloric acid on the alcohol and is a liquid, which 
boils at 230°4 and is reduced to cymene by zine and hydro- 
chloric acid. A cymyl chloride, which probably contains the 
normal propyl group, is obtained by the action of chlorine on 
boiling cymene. According to Errera, two other isomeric 
chlorides are also formed (p. 291); if the mixture, which boils at 
225°—229°, be boiled with water and lead nitrate, cuminaldehyde 
(CH,),CH.C,H,.CHO, is obtained.® 

Cymyl ethyl ether, C,H,.C,H,.CH,OC,H,, was obtained by 
Errera, together with allyltoluene, by boiling the chlorides with 
alcoholic potash, as a liquid, boiling at 227°. 

1 Jesurun, Ber. Deutsch. Chem. Ges. xix. 1413. 
2 Kelbe and Warth, Ann. Chem. Pharm, ccxxi. 157. 
3 Tbid. xcii. 66 ; ecxcii. 224. 


4 Rossi, ibid. Suppl. i. 189 ; Paternd and Spica, Gaz. Chim. Ital. ix. 397. 
5 Ibid. xiv. 277. 


304 AROMATIC COMPOUNDS. 


Dicymyl ether or Cumin ether, (C,H,.C,H,.CH,),0, is formed 
when a few drops of dilute sulphuric acid are added to the 
alcohol and the mixture heated to 200° and then distilled. 
It may also be obtained by the action of sodium cymylate 
on cymyl chloride, and is a liquid which has a sweet smell, 
boils at about 350°, and is partially decomposed by distillation 
into cymene and cuminaldeyde, the decomposition being almost 
complete after several redistillations.? 

Cymyl acetate, C,H,.C,H,CH,OC,H,O, was prepared by 
Czumpelik by heating the impure chloride obtained from 
cymene with potassium acetate. It is a liquid, which boils at 
236° and smells like rose-wood oil? 

Cymylamine, C,H,.C,H,.CH,.NH,, is formed, together Seth 
the secondary arti tabtines bases by heating the éhlomte with 
ammonia (Rossi). Czumpelik obtained it iy the action of zine 
and hydrochloric acid on thio-cuminamide, C,H,.C,H,.CS.NH, 
(p. 307),? and Raab by distilling cymylcarbimide, prepared 
from cymyl chloride and silver cyanate, with caustic potash.* 

It is however best prepared by the action of sodium amalgam 
and acetic acid on cuminaldoxime, which is described below.® 
It is a liquid, which has an ammoniacal odour and boils at 
226°—227°. | | 

Cymyl mustard oil, C,H,.C,H,.CH,.NCS, has a faint but 
distinct smell of mustard, and decomposes on distillation 


(Raab). 


THE PROPYLBENZOIC ACIDS. 


2445 Cuminol or Cuminaldehyde, (CH,),CH.C,H,.CHO, occurs, 
as previously mentioned, in the ethereal oil of the Roman cumin 
and the seeds of the hemlock accompanied by cymene, from 
which it is probably formed by oxidation (Widman). It is pre- 
pared from Roman cumin oil by agitating the portion which boils 
above 190° with a saturated solution of sodium sulphite, washing 
the granular crystalline precipitate, which has separated after 
twenty-four hours, with ether and decomposing it by dis- 


1 Rileti, Gaz. Chim. Ital. xiv. 469. 

* Ber. Deutsch. Chem. Ges. iii. 480. 

5 Lod WS 8he 

4 Tbid. viii. 1148 ; x. 52. 

° Goldschmidt and Gessner, ibid. xx. 2413. 


CUMINOL. 305 


tillation with sodium carbonate solution or dilute sulphuric 
acid, 

Cuminol is an oily liquid, which has the smell of Roman 
cumin oil, boils at 236°5°? and readily oxidizes in the air. It 
produces a violet-red colouration in a solution of fuchsin which 
has been decolourized by sulphurous acid.? Its derivatives 
resemble those of benzaldehyde. 

Cuminaldoxime, (CH,),CH.C,H,CH(NOH), forms crystals, 
which melt at 52°4 

Metanitrocuminol, (CH,),CH.C,H.(NO,)CHO, is formed by 
the action of a cooled mixture of nitric and sulphuric acids on 
the aldehyde and crystallizes in oblique, sulphur-yellow prisms, 
melting at 54°.° 

Orthonitrocuminol has been obtained by the oxidation of 
orthonitrocumenylic acid, (CH,),CH.C;H,(NO,)CH—CH.CO,H, 
with potassium permanganate. It is an oily liquid, and yields a 
blue colouring matter on heating with acetone and caustic soda, 
which is undoubtedly di-isopropylindigo.® 

Para-isopropylbenzore acid, (CH;),CH.C,H,.CO,H. Chevallier 
discovered an acid in an old sample of Roman cumin oil which 
had become sour, which resembled succinic acid and was un- 
doubtedly cuminic acid.’ It was then prepared by Gerhardt 
and Cahours by allowing cuminol to drop on to fused caustic 
potash, and is also formed, according to these chemists, by the 
oxidation of cuminol in the air, especially in presence of an 
alkali, and by the action of potassium chromate and sulphuric 
acid and other oxidizing agents.® 

In order to prepare it, Roman cumin oil is allowed to drop on 
to an equal weight of fused caustic potash contaimed in an iron 
retort, the mass allowed to cool as soon as the evolution of 
hydrogen ceases, water added and the unattacked oil distilled 
off. The cuminic acid is separated from the residue with hydro- 
chloric acid and purified by conversion into the calcium or 
magnesium salt.® 

It may also be readily obtained by agitating 6 parts of 


1 Kraut, Ann. Chem. Pharm. xcii. 66. 

2H. Kopp, zbid. xciv. 317 ; Meyer, Ber. Deutsch. Chem. Gres. x. 150. 
3 Schmidt, zbéd. xiv. 1850. 

4 Westenberger, ibid. xvi. 2994. 

5 Lippmann and Strecker, bid. xii. 76. 

§ Einhorn and Hess, ibid. xvii. 2019. 

7 Kraut, Gmelin’s Org. Chem. vii. 143. 

8 Ann. Chem. Pharm. xxxviii. 72. 

® Beilstein and Kuppfer, ibid. clxx. 301. 


306 AROMATIC COMPOUNDS. 





cuminol with 30 parts of caustic soda solution of sp. gr. 1:25, 
and adding a solution of 10 parts of potassium permanganate 
in 250 parts of water, with constant agitation. After a few 
hours, a little alcohol is added in order to reduce any excess of per- 
manganic acid, the manganese oxide being then filtered off and the 
cuminic acid precipitated with hydrochloric acid.’ It is obtained 
synthetically by the action of carbon dioxide on a mixture of 
bromocumene and sodium.” 

It is scarcely soluble in cold, only slightly in hot water and 
crystallizes from alcohol in asymmetric tablets, which melt 
at 116°5° and readily sublime in long needles, which have an 
acid taste and a characteristic faint odour of bugs. 

It volatilizes with steam and is oxidized to terephthalic acid 
by chromic acid and to hydroxyisopropyl-benzoic acid, 
(CH,),C(OH)C,H,CO,H, by potassium permanganate. On 
distillation with lime it decomposes into cumene and carbon 
dioxide and when internally administered appears unaltered in 
the urime, while cymene is converted into cuminic acid in the 
human organism? and chiefly into cuminuric acid in that of 
the dog.* 

Its salts have been investigated by Gerhardt and Cahours, and 
by Beilstein and Kupffer. 

-Lihyl cuminate, (CH,),CH.C,H,.CO.C,H,;, is a liquid, which 
smells like apples and boils at 240°. 

2446 Cumoyl chloride, (CH,),CH.C,H,COCI, is a mobile 
liquid, boiling at 256°—258°,° which is well fitted to serve as 
the starting point in the preparation of the cuminic ethers and 
other derivatives. 

Cuminie anhydride, (C,H,.C,H,.CO),O, is a thick, oily liquid, 
which deposits crystals when preserved for a long time.® 

Cuminamide, (CH,),CH.C,H,.CO.NH,, crystallizes from hot 
water in lustrous tablets or long needles, which are insoluble in 
cold water.’ It may be prepared synthetically from wrea chloride, 
CICO.NH, (a substance which is obtained when ammonium 
chloride is heated in a current of carboxyl chloride and forms 
compact needles, melting at 50°), by bringing this into contact 


} Meyer and Rosicki, Ber. Dewtsch. Chem. Ges. xi. 1790; Ann. Chem. Pharm. 
COXIX. 243. 


2 R. Meyer, Journ. Prakt, Ohem. [2] xxxiv. 93. 

3 Nencki and Ziegler, Ber. Deutsch. Chem. Ges. v. 750; Gerichten, ibid. xi. 
369, 4 Jacobsen, ibid. xii. 1512. 

° Cahours, Ann. Chem. Pharm. 1xx. 45. 6 Gerhardt, 7bid. lxxxvii. 77. 


7 Field, ibid, Ixv. 49; Gerhardt, zbid. Ixxxvii. 167 ; Gerhardt and Chiozza, 
ibid. Ixxxvii. 299. 


NITROCUMINIC ACIDS. 307 


with cumene and carbon disulphide, gradually adding aluminium 
chloride and finally heating the mixture : 


(CH,),CH.C,H, + CICO.NH, =(CH,),CH.C,H,.CO.NH + HCl. 


It melts at 153°5° (Fileti) and is converted into cuminic acid 
by boiling with caustic potash solution. Several other aromatic 
acids have been prepared by this reaction.’ 

Thiocuminamide, (CH,),CH.C,H,CS.NH,, is obtained by 
passing sulphuretted hydrogen into an alcoholic, ammoniacal 
solution of cumonitril; it forms needles, which are soluble in 
hot alcohol.? 

Cumomitril, (CH;),CH.C,H,.CN, is formed by heating the 
amide (Field) and by the action of cyanogen bromide on 
potassium cuminate : * 


C,H,.C,H,CO,K + CNBr = C,H,.C,H,CN + CO, + KBr. 


It is also obtained, together with the amide,* by heating cuminic 
acid with potassium thiocyanate ° (Pt. IV. p. 197). 

It is an aromatic smelling liquid, which has a burning taste 
and boils at 243°—244°. 

Cuminurice acid, (OH,),CH.C,H,.CO.NHCH,.CO,H, was pre- 
pared by Cahours by the action of cumoyl chloride on silver 
amido-acetate,® and was found by Jacobsen in the urine of dogs 
after the administration of cymene. It crystallizes from hot 
water in large, iridescent plates, which melt at 168° and are 
decomposed into cuminic acid and amido-acetic acid by heating 
with hydrochloric acid to 120°. 

Orthonitrocuminic acid, (CH,),CH.C,H,(NO,)CO,H (4:2 :1), 
was obtained by Widman by the oxidation of orthonitrocumenyl- 
acrylic acid, (CH,),CH.C,H,(NO,)C,H,.CO,H, with chromic acid 
or potassium permanganate. It is very readily soluble in 
alcohol, but with difficulty in petroleum-spiit, and crystallizes 
from acetic acid of 50 per cent. in slightly oblique, lustrous, 
_ colourless tablets, which melt at 99°.’ 

Metanitrocuminic acid (4: 3:1) is formed by the action of 
fuming nitric acid on cuminic acid,® and by the oxidation of 
1 Gattermann and Schmidt, Ber, Dewtsch. Chem, Ges. xx. 858. 

2 Czumpelik, bid. ii. 185. 

3 Cahours, Ann. Chem. Pharm. eviii. 320, 

4 Fileti, Ber. Deutsch. Chem. Ges. xx. Ref. 138. 
5 Letts, zbid. vi. 674. 

6 Ann. Chem. Pharm. cix. 31. 

7 Ber. Deutsch. Chem. Ges. xix. 269. 

8 Cahours, dnn. Chem. Pharm. |xix, 248. 


308 AROMATIC COMPOUNDS. 


nitrocuminol with chromic acid.t It crystallizes from nitrie acid 
or alcohol in monosymmetric prisms, melting at 158°. It changes 
in the sunlight to a red, amorphous substance, which also 
possesses acid properties.” 

Orthamidocuminic acid, (CH,),CH.C,H,(NH,)CO,H, was pre- 
pared by Widman from the nitro-acid by reduction with ammonia 
and ferrous sulphate. It crystallizes in long tablets or quadratic 
plates, which melt at 93°—94". 

Metamidocuminie acid is formed by the reduction of meta- 
nitrocuminic acid with ammonium sulphide or ammonia and 
ferrous sulphate, and crystallizes in brownish needles, melting 
abd 29).° 

2447 Orthocuminic acid or Ortho-isopropylbenzoic acid is obtained 
when the potassium or barium salt of cumene-orthosulphonic 
acid is fused with sodium formate. It is insoluble in cold water, 
separates from alcohol or ether in an indistinctly crystalline 
mass, volatilizes with steam, sublimes when carefully heated 
and decomposes at a higher temperature without previously 
melting. It is not attacked by aqueous chromic acid solution 
even on heating, while a solution of chromium trioxide in acetic 
acid oxidizes it to carbon dioxide and water, and alkaline potas- 
sium permanganate converts it into phthalic acid.* 

Parapropyibenzote acid, C.H,.C,H,.CO,H, has been obtained 
by Paterno and Spica as a product of the oxidation of propyl- 
isopropylbenzene,> and by Korner from paradipropylbenzene.® 
R. Meyer has also prepared it by the action of carbon dioxide 
on a mixture of sodium and parabromopropylbenzene.’ It erys- 
tallizes from hot water in very lustrous plates, which consist of 
microscopic, monosymmetric prisms, and separates from alcohol 
in more compact crystals of the same form, which melt at 140° 
and readily sublime in long, broad needles. It is oxidized by 
potassium permanganate to terephthalic acid (R. Meyer). 

Orthomitroparapropylbenzote acid, C,H,.C,H,(NO,)COOH, is 
formed by the oxidation of orthonitroparapropylcinnamic acid, 
C,H,.C,H,(NO,)C,H,.CO,H, with chromic acid and potassium 
permanganate and crystallizes from alcohol in rhombic tablets, 
melting at 156°—157'5°.8 ith 

1 Lippmann and Strecker, Ber. Deutsch. Chem. Ges. xii. 76. 

2 Paternd and Fileti, zbid. ix. 81. 

* Cahours, Ann. Chem. Pharm. cix. 10; Paternd and Fileti, Ber. Deutsch 
Chem. Ges. vii. 81 ; Lippmann and Lange, <bid. xiii. 1660. 

4 Claus and Schulte, 7bid. xix. 3012. 

5 Ibid. x. 1746: 6 Tbid. xi. 1863. 7 Journ. Prakt. Chem. [2] xxxiv. 101. 

8 Widman, Ber. Deutsch. Chem. Ges. xix. 276. 


PROPYLHYDROXYBENZOIC ACIDS. 309 


Orthopropylbenzore acid is obtained by heating phthalylpropionic 
acid to 200° with hydriodic acid and amorphous phosphorus : 


ieee ge Gott ater 
pea 


"HCHO, 
C,H + CO, + 2I,. 


*\C0.0H 


It crystallizes from dilute alcohol in small plates, which melt 
at 53°} 


PROPYLHYDROXYBENZOIC ACIDS. 


2448 Orthohydroxycuminic acid, (CH,),CH.C,H,(0H)CO,H 
(4:2:1). Jacobsen, by fusing para-isocymenesulphonic acid, 
which is formed in preponderating amount in the sulphonation 
of cymene, with potash, obtained hydroxycwminic acid, melting 
at 88°,? while isohydroxycuminic acid,’ melting at 93°, was formed 
by gently heating carvacrol, the two acids resembling each other 
very closely. They are, indeed, obviously identical, since the 
normal propyl is converted into the iso-group by the oxidation 
of carvacrol. The same acid is therefore obtained by the action 
of nitrous acid on orthamidocuminic acid* and by the addition 
of hydrogen to propenylsalicylic acid,> C,H,;.C,H,(OH)CO,H. 
It separates from hot water in flat needles or plates, which melt 
at 96°, readily volatilize with steam, give a reddish violet coloura- 
tion with ferric chloride and decompose into metacumophenol 
and carbon dioxide on heating with hydrochloric acid. 

Metahydroxycuminic acid (4: 3:1), was obtamed by Barth, 
who named it thymoxycwminic acid, by fusing thymol with 
caustic potash.® It is also formed by the action of nitrous acid 
on metamidocuminic acid,’ and when the potassium salt of 
thymylsulphuric acid or thymylphosphoric acid is oxidized with 
alkaline potassium permanganate (Heymann and Konigs). 

1 Gabriel and Michael, Ber. Dewtsch. Chem. Ges, xi. 104. 
2 Ibid. xii. 429. 

3 Ibid, xi. 1058. 

4 Widman, ibid. xix. 252 and 270. 

5 Heymann and Konigs, zbid. xix. 3304; xx. 2390. 


© Ibid. xi. 1569. 
7 Cahours, loc. cié.; Lippmann and Lange, Joc. cit. 


310 AROMATIC COMPOUNDS. 





It crystallizes from hot water in long, thin needles, which 
melt at 143°. Ferric chloride produces an opalescence in the 
dilute, aqueous solution, but a precipitate in one of greater 
concentration. On continued fusion with caustic potash, it is 
converted into -hydroxyterephthalic acid, while hydrochloric acid 
has no action upon it even at 200°. 

Para-isopropylphenolearboxylic acid (5:2:1) is formed by 
the action of carbon dioxide and sodium on paracumophenol 
and crystallizes in nacreous plates or flat needles, which melt at 
120°5° and are much more readily soluble in hot than in cold 
water. Its aqueous solution is coloured deep bluish violet by 
ferric chloride. 

Ortho-isopropylphenolcarboxylic acid (6: 2:1) has been pre- 
pared from orthocumophenol and crystallizes in needles, melting 
at 71°—72°? 

Parapropylphenolearboxylic acid, C,H,.C,H,(0H)CO,H 
(5:2:1), is obtained from parapropylphenol ; it melts at 98° 
and gives a violet colouration with ferric chloride. 

Orthopropylphenolcarboxylic acid (3: 2:1) melts at 93°—94"3 


“ 


HYDROXYPROPYLBENZOIC ACIDS. 


2449 Hydroxyisopropylbenzoic acid, (CH,),C(OH)C,H,.CO,H. 
This tertiary alcohol-acid is formed, together with a small 
quantity of terephthalic acid, by the oxidation of an alkaline 
solution of cuminic acid with potassium permanganate,* and also 
when cymene is heated with a strongly alkaline solution of the 
same reagent.? It is readily soluble in hot water, and crystal- 
lizes from a not too concentrated solution in thin, asymmetric 
prisms, which melt at 155°—156°. It is oxidized by chromic 
acid to acetylbenzoic acid and terephthalic acid and decomposes 
into water and propenylbenzoic acid on heating with hydrochloric 
acid or acetic anhydride.® 

Hydroxyisopropylsulphobenzore acid, (CH,),C(OH)C,H.(SO,H) 
CO,H, is obtained when cymenesulphonic acid or para-iso- 

1 Paternd and Mazzara, Gaz. Chim. Ital. viii. 389. 

* Fileti, 2bid. xvi. 113. 3 Spica, ibid. viii. 406. 


a R. Meyer, Ber, Deutsch. Chem. Ges. xi. 1283; Ann. Chem. Pharm. ccxix. 
8 


> Bladin and Widman, Ber. Deutsch. Chem, Ges. xix. 252 and 583. 
® Meyer and Rosicki, ibid. xi. 1791, 2172; Ann. Chem. Pharm. loc. cit. 


TOLYLPROPIONIC ACIDS. 311 


cymenesulphonic acid is oxidized with potassium permanganate. 
Its potassium salt, C,,H,,SO,K, + 5H,0O, crystallizes in large, 
thick, asymmetric tablets. 

Hydroxyisopropylmetanitrobenzoie acid, (CH,),C(OH)C,H, 
(NO,)CO,H, is formed by the oxidation of metanitrocuminic 
acid or nitrocuminol with potassium permanganate. It crystal- 
lizes from hot water in long, transparent, brittle needles, which 
melt at 190°—191° and become brown in the light.” 

Hydroxyisopropylmetamidobenzoie acid, (CH,),C(OH)C,H, 
(NH,)CO,H, is the product of the action of ferrous sulphate 
on an ammoniacal solution of the nitro-acid. It crystallizes 
from ether in lustrous prisms, which do not melt below 270° and 
are readily soluble in water and alcohol.® 

Hydroxyrsopropylorthonitrobenzorve acid crystallizes from ether 
in oblong tablets and melts at 168°. 

Hydroxyrsopropylorthamidobenzore acid forms colourless prisms, 
melting at 158° and yields a blue fluorescent ethereal solution.* 

Hydroxyisopropylsalicylie acid, (CH,),C(OH)C,H.(0H)CO,H 
(CO,H :OH=1:2). The potassium salts of thymylsulphuric 
and thymylphosphoric acids are converted by oxidation with 
potassium permanganate into metahydroxycuminic acid, while 
on the other hand, the corresponding carvacrol derivatives yield 
hydroxyisopropylsalicylic acid. This substance crystallizes from 
hot water in large, flat needles, which melt at 130°—135° and 
are converted by continued heating or by boiling with dilute 
hydrochloric acid into propenylsalicylic acid, C,H,.C,H;(OH) 
CO,H, which is reduced by nascent hydrogen to orthohydroxy- 


cuminic acid.® 


TOLYLPROPIONIC ACIDS, CH,.C,H,.C,H,.CO,H. 


2450 Metatolylpropionic acid is formed by the oxidation of 
meta-isobutyltoluene, CH,.C,H,.CH,CH(CH,),, with nitric acid 
and crystallizes from hot water in white needles, which melt at 
125° and readily sublime.® 


1 Meyer, Ann. Chem. Pharm. ccxx. 9. 

2 Widman, Ber. Deutsch. Chem. Ges. xv. 2547. 

3 Ibid. xvi. 2569. 

4 Ibid. xix. 269. 

5 Heymann and Konigs, zbid. xix. 3304 ; xx. 2390. 
6 Effront, ibid. xvii. 2330, 


286 


312 AROMATIC COMPOUNDS. 


Parapropylpropionaldehyde, CH;.C,H,.C,H,-CHO, was obtained 
by Etard from cymene, which peti: iM isonet chloride to 
form cumidenedichlorochromic acid, CH,.C,H,.CH,.CH »CH(OCr 
Cl,.0H),, a chocolate-brown, petals arian ‘which 1s 
decomposed by water with formation of the aldehyde, which 
he mistook for cuminol It is a colourless, strongly refractive 
liquid, which boils at 222°—223°, has a peppermint-like odour 
and colours fuchsinsulphurous acid violet. 

On continued boiling with nitric acid, it is nea to para- 
toluic acid and is tetas into terephthalic acid by potassium 
permanganate.” 


wae SE 
DIBASIC ACIDS, LC , AND THEIR 
GH GO. 
DERIVATIVES. 


2451 Methylhomophthalic acid. When homo-orthophthalonitril 
(p. 152) is treated in well-cooled alcoholic solution with methyl 
iodide and alcoholic potash, and the mixture then gently heated, 
methylhomophthalonitril is formed : 


CN CN 
CHC + CH;t = CHK 
CH,.CN CH(CH,)ON 
It forms large, asymmetric crystals, melts at 36°—37°, boils at 
284°—286°, and is converted by sulphuric acid into the corre- 
sponding imid, which is converted by heating to 200° with 
hydrochloric acid into methylhomophthalic acid, which separates 
from hot water as a crystalline powder, melting at 146°—147°8 
Hydrocinnamorthocarboxylic acid is formed by the combination 
of hydrogen with cinnamocarboxylic acid, C,H,(CO,H)CH— 
‘CH.CO,H, and crystallizes from hot water in long, lustrous 
needles, melting at 165°—166°.4 
Benzhydrylacetocarboaxylic acid, CO,H.C,H,.CH(OH)CH,CO,H. 
The lactone of this acid is formed by the action of sodium 
amalgam and water on phthalylacetic acid : 


+ HL. 


Cc ug > SO rea He 
C—CH—CO,H 
1 Ann. Chim. Phys. [5] xxii. 259. 
2 Richter and Schiichner, Ber. Deutsch. Chem. Ges. xvii. 1391. 
3 Gabriel, ibid, xx. 2499. 
“ Gabriel and Michael, ibid. x. 2199. 


Ss Sete} 


OPIANYLACETIC ACID. 313 


This latter substance is readily soluble in hot water and 
alcohol, and crystallizes with one molecule of water in lustrous 
needles, which become anhydrous at 100°, and melt at 150°— 
151°. It is a monobasic acid, but yields salts of the dibasic 
benzhydrylacetocarboxylic acid, which does not exist in the free 
state, with strong alkalis. These salts change at a temperature 
of 220°—240° into those of cinnamocarboxylic acid, while 
inversely, this acid is converted by fusion into the isomeric 
lactone :1 


CO.0H 0 
H sagas Poste | 
Perot COOH”  ~ \Gn-CH_CO.OH 


CO,H 
Opianylacetic acid, (CH,0), CHC 

CH(OH)CH,.CO,H 
unknown in the free state. Its lactone, meconinacetic acid is 
formed by heating opianic acid with malonic acid, glacial acetic 
acid and sodium acetate. 


, 1s also 


60.08 OH 
(CH,0),C,H, + CH 
3 2 wi "\CO. are 
(CH,0),C, WC S0 + CO, + H,0. 
CH—CH,.CO,H 


It crystallizes from hot water in lustrous needles, which melt 
at 167°. On boiling with baryta water, barium opianylacetate 
is formed and yields meconinacetic acid again when decom- 
posed by an acid. If the latter be heated with hydriodic acid, 
normeconinacetic acid is formed : 


HO)CHK > ‘SO 
H—CH,.CO,H 


This crystallizes from hot water in long tablets, melting at 
293) 4 
1 Ber. Deutsch. Chem. Ges. x. 1558 and 2199, 
2 Liebermann and Kleemann, 7bid. xix. 2290. 


314 AROMATIC COMPOUNDS. 





METHYLPROPENYLBENZENE AND ITS 
DERIVATIVES. 


2452 Methylpropenylbenzene, CH,.C,H,.CH—CH.CH,. | This 
hydrocarbon, which is also known as allyltolwene, is formed when 
the product obtained by chlorinating boiling cymene is heated 
with alcoholic potash. It is a liquid, boiling at 192°, which is 
oxidized by potassium permanganate to paratoluic acid and 
behaves in a similar manner to styrolene, since it changes when 
preserved or kept in contact with calcium chloride into the 
amorphous meta-allyltoluene, which is re-converted into allyl- 
toluene on distillation. The latter undergoes condensation on 
heating with hydrobromic acid, di-allyltolwene, a liquid, which 
boils at 350°, being formed.? 

Metamethyleinnamie acid, CH,.C,H,CH—CH.CO,H, which 
has also been named ¢olylacrylic acid, is obtained by heating 
metatolualdehyde with acetic anhydride and sodium acetate and 
crystallizes from boiling water in silky needles, which melt at 
110°—111°. Its ammonium salt gives an egg-yellow precipitate 
with ferric chloride, similar to that which is given by ammonium 
cinnamate.” 

| sera 
Homo-umbelliferon, CH .C,H,(OH) | , is formed 
\cCH= CH 
when equal molecules of orcinol and malic acid are heated with 
sulphuric acid. It is insoluble in water, readily soluble in 
alcohol, and crystallizes from acetone in yellowish tablets, 
melting at 248°, the solution of which in alkalis or sulphuric 
acid has a blue fluorescence. On fusion with potash, it yields 
orcylaldehyde and acetic. acid.® 

Propenylbenzote acid, C,H,.C;H,.CO,H, is prepared by heating 

hydroxyisopropylbenzoic acid with dilute hydrochloric acid : 


on ee 
H)C,H,,. = —C,H,.C : 
on’ JG,H. COs oH C,H,.CO,H + H,O 
It is insoluble in cold and only slightly soluble m hot water, 
readily soluble in alcohol, crystallizing from dilute alcohol in 


1 Errera, Gaz. Chim. Ital. xiv. 277 and 504. 
? Bornemann, Ber. Deutsch. Chem. Ges. xvii. 1474; xx. 1882. 
3 Pechmann and Welsh, ¢bid. xvii. 1646. 


ISOPROPENYLBENZOIC ACID. 315 





small plates or needles, which have a satin lustre and melt at 
160°—161°. It is reconverted into cuminic acid by sodium 
amalgam and water. 

Lsopropenylbenzorie acid is formed when stronger hydrochloric 
acid is employed in the above reaction and is insoluble in water, 
It crystallizes from hot alcohol in stellate groups of microscopic 
needles, which melt at 255°—256°. It is unattacked by water 
and sodium amalgam, but is converted into cuminic acid by 
heating with hydriodic acid and phosphorus. It probably stands 
in a similar relation to propenylbenzoic acid as does isatropic 
to atropic acid (p. 233) and has perhaps the following con- 


stitution :? 
CO,H CH, 


| | 
C.H,—C—CH, 
C,H,—C—CH, 
CO,H CH, 


Propenylsalicylie acid, C,H;.C,H,(OH)CO,H, is best obtained 
by heating hydroxyisopropylsalicylic acid with dilute hydro- 
chloric acid : 


2 


OH we 
CoH y(OH)C AH, = CH(OHK | CH, + H,0. 
C(OH) CK 
CH, CH, 


It is also only slightly soluble in hot water and crystallizes 
from carbon disulphide in fine needles, which melt at 145°—146°. 
It sublimes at 150° with slight decomposition, is volatile with 
steam and gives a deep reddish violet colouration with ferric 
chloride. Sodium amalgam and water convert it into ortho- 
hydroxycuminic acid.? 

Hugetime acid, C,H,.C,H,(0H)(OCH;)CO,H, is formed by the 
action of carbon dioxide and sodium on eugenol and crystallizes 
from water in long, thin prisms, which melt at 124° and decom- 
pose when heated for some time into carbon dioxide and eugenol 
(p. 197). Its aqueous solution is coloured deep blue by ferric 
chloride.® 

Methyleugetinic acid, C,H,;.C,H,(OCH,),CO,H. The ethyl 


1 R. Meyer and Rosicki, Ann. Chem. Pharm.«cexix. 270. 
* Heymann and Konigs, Ber. Deutsch. Chem. Ges. xix. 3304 ; xx. 2390. 
3 Scheuch, Ann. Chem. Pharm. exxv. 17. 


316 AROMATIC COMPOUNDS. 





ether of this acid is formed when methylbromeugenol is treated 
with sodium and ethyl chlorocarbonate. The free acid forms 
broad, yellow crystals, which melt at 180° and are difficultly 
soluble in water." 

2453 Phthalylacetic acid is obtained when phthalic anhydride 
is heated with sodium acetate and acetic anhydride: 


ia Masa 
BRAG G70 st CH, UO seis aaa ee + H,0. 
Gc CH. LORE 
It separates from alcohol, in which it is only slightly soluble, 
in distorted crystals, while it crystallizes from glacial acetic acid, 
or better nitrobenzene, in broad needles,? which melt above 260° 
and decompose at 276° with evolution of gas.’ 

_ Cinnamocarboaylic acid, CO,H.C,H,.CH—CH.CO,H. The 
formation of this acid from benzhydrylacetocarboxylic acid has 
already been mentioned (p. 313); it crystallizes from hot water 
in fine needles, which melt at 173°—175° and are thus converted 
into the lactone of benzhydrylacetocarboxylic acid. 

Benzoylacetocarboxylic acid is formed by the action of alkalis 
on phthalylacetic acid : 


eG CO.OH 


4 HO ie HCE 
ON OHCOH in. SOO CH COL 


It crystallizes from hot water in vitreous needles, which melt 
at 90° and on further heating or on boiling with water are 
resolved into carbon dioxide and acetophenonecarboxylic acid. 

Phihalimidylacetic acid is the product of the action of ammonia 
on phthalylacetic acid : 


Mat 
HK +NH, = O51,¢ >NH +H,0. 
a CH. CO,H Ca LOSE 
It crystallizes from hot water in silky needles, which melt at 
200° with evolution of gas.* 


1 Wassermann, Ber. Deutsch. Chem. Ges. x. 237 ; Compt. Rend. lxxxviii. 1206. 

2 Gabriel and Michael, Ber. Deutsch. Chem. Ges. x. 891 and 1551. 

3 Roser, ibid. xvii. 2619. 

* Gabriel and Michael, Joc. cit. ; Roser, Ber. Deutsch. Chem. Ges. xvii. 2623 ; 
Gabriel, zbid. xviii. 2451. 


PHTHALMETHIMIDYLACETIC ACID. 317 


Phthalmethimidylacetic acid. When phthalylacetic acid is 
treated with a solution of methylamine, the liquid being well 
cooled during the operation, methylamidobenzoylacetocarboxylic 
acid is formed : 


as CO.NH.CH, 
CHC > + H,N.CH, = CoH, 
aon CO,H CO.CH,.CO,H. 


This substance forms a crystalline powder consisting of small 


prisms and is converted into phthalmethimidylacetic acid by cold 
sulphuric acid : 


/OO.NECH, _ y's 
HC HK | SNOH, + H,0. 
CO.CH,.CO,H — C—CH.CO,H 


The body separates out when the solution is allowed to stand 
for some time and is then poured into water, and crystallizes 
from alcohol in silky needles, which decompose on heating into 
carbon dioxide and methylenephthalmethimidine ; 


PB JO 
Ene >NCH, = CO, + C, HS Kz: Pon 
C—CH.CO,H 


It is left behind as a syrup and soon solidifies to a hard 
crystalline mass, which melts even with the heat of the hand 
and volatilizes with steam, its vapour having a pungent odour. 
If the clear distillate be extracted with ether and the latter 
evaporated, the imidine is obtained in transparent, pointed 
prisms, which, however, soon become clouded and _ soft, while 
needles of a substance which is not volatile with steam are 
deposited if the aqueous solution be allowed to stand. 


BAAN 
Phthalmethimidylacetic acid, C,H NC,H, . Ethyl- 


‘\ o Zonc6,H1 
amine reacts with phthalylacetic acid differently fare methyl- 
amine, two molecules of each combining to form a substance 
C,,H,,N,O;, with elimination of carbon dioxide and water. 
This body crystallizes from lukewarm alcohol in needles, which 
melt and froth up at 129°. It is converted by cold sulphuric 
acid into the acid, which crystallizes from alcohol in yellow 
needles, melting at 180° with evolution of gas. 

In the formation of this acid one molecule of water and one 
of methylenephthalmethimidine are withdrawn from the original 


318 AROMATIC COMPOUNDS. 


condensation product and the same imidine is also formed when 
this body is heated above its melting point, carbon dioxide and 
water being eliminated. It is an oily liquid, which smells like 
fresh carrots and is volatile with steam. 

Propylamine behaves towards phthalylacetic acid in a similar 
manner to ethylamine, while secondary and tertiary amines 
simply form salts. 

Methylenephthalphenimidine. When aniline and phthalylacetic 
acid are brought together, carbon dioxide is evolved and if the 
reaction be completed on the water-bath and the liquid allowed to 
stand for twenty-four hours, the anilide of acetophenone-ortho- 
carboxylic acid, C,,H,,NO,, separates out. This body crystallizes 
from hot alcohol or benzene in large, colourless cubes, melting at 
189°—192°, and is decomposed into water and methylene- 
phthalphenimidine when gradually heated to 230°, aniline being 
at the same time formed in a secondary reaction : 


/OO.NE.OH, oo 
CH = H,0 + GH >NCH, 
CO.CH, C—CH, 


Methylenephthalphenimidine cfystallizes from alcohol in 
yellowish prisms, melting at 100°. If the anilide be treated 
with sulphuric acid, a substance isomeric with the imidine is 
formed, melting at 265.°? 


THE BUTYLBENZENES. 


2454 Butylbenzene, C,H;.CH,.CH,.CH,.CH,, is formed by the 
action of sodium on a mixture of propyl bromide and benzyl 
bromide,? or of butyl bromide and bromobenzene.? It is a liquid, 
which has a very pleasant odour, boils at 180°, and has a sp. gr. 
of 0°875 at 0° and of 0°8622 at 16°. 

a-Isobutylbenzene, C,H;.CH,CH(CH,),, is obtained by treating 
a, mixture of bromobenzene and isobutyl bromide‘ or isobutyl 
iodide,> or of benzyl chloride and isopropyl iodide,® with sodium. 

Itis also formed by heating isobutyl alcohol with benzene and 


1 Mertens, Ber. Deutsch. Chem. Gres. xix. 2367. 
2 Radziszewski, zbid. ix. 260. 

3 Balbiano, zbid. x. 296. 

4 Riess, ibzd. iii. 779. 

5 Wreden and Znatowicz, ibid. ix. 1606. 

6 Aronheim and Kohler, <bid. viii. 509. 


THE BUTYLBENZENES. 319 





zinc chloride,} and by the action of aluminium chloride on a 
mixture of isobutyl chloride and benzene.? 

It is a pleasant smelling liquid, which boils at 167-5° and has 

a sp. gr. of 0°890 at 15° (Radcisnewslay 

a-Isobutylpara-vodobenzene, C,H ,I.C,H,(CH,),, was obtained by 
Pahl from the amido-compound by means of the diazo-reaction. 
It forms a radiating crystalline mass which has an aromatic 
odour and boils at 255°—256°. It is oxidized by nitric acid to 
para-iodobenzoic acid.? 

Isobutylphenol, C,H,(OH)C,H;(CH,),, is formed by heating 
phenol with isobutyl alcohol and zinc chloride,* as well as by the 
action of nitrous acid on isobutylamidobenzene. It crystallizes in 
needles, melting at 99°, boils at 236°,° has a faint, not unpleasant 
odour and gives no colouration with ferric chloride. On heat- 
ing with phosphorus pentoxide it is resolved into phenol and 
isobutylene. 

Isobutylparamidobenzene, C,H,(NH,)C,H.(CH,),, is obtained 
by heating aniline hydrochloride with isobutyl alcohol to 230° © 
and also by heating isobutylphenol with zinc bromide-ammonia 
and ammonium bromide to 320°—330°." It is a faintly odorous 
liquid, boiling at 235°—237°; its hydrochloride is stable in the 
air and crystallizes in fine tablets. 

Nitramido-isobutylbenzene, C,H,(NO,)(NH,)C,H,, forms red- 
dish yellow crystals, melts at 106°5° and is converted by re- 
duction into diamido-isobutylbenzene, C,H,(NH,),C,H5, which 
crystallizes from hot water in thick, micaceous tablets or plates, 
melts at 97°5° and boils at 280°—282°. Its general behaviour 
shows that the amido-groups are in the ortho-position.® 

Phenisobutyl mustard oil, C,H, NCS)C,H,(CH,),, crystallizes 
from petroleum-spirit in needles, melting at 42° and boils at 
277° (Pahl). 

B-Isobutylbenzene, C,H;.CH(C,H,)CH,, was obtained by 
Radziszewski by the action of zinc ethyl on secondary phenyl- 
ethyl bromide as a liquid, which possesses a characteristic odour, 
boils at 170°—172° and has a sp. gr. of 0°8726 at 16°. 


1 Goldschmidt, Ber. Deutsch. Chem. Ges. xv. 1066 and 1425. 
2 Gossin, Bull. Soc. Chim. xli. 446. 

3 Pahl, Ber, Dewtsch. Chem. Ges. xvii. 1232. 

$ Liebmann, ibid. xiv. 1842. 

5 y. Dobrzycki, Jowrn. Prakt. Chem. [2] xxxvi. 390. 

6 Studer, Ann. Chem. Pharm. cexi. 234. 

7 RK. Lloyd, Ber. Deutsch. Chem. Ges. xx. 1254, 

8 Gelzer, ibid. xx. 3253. 


320 AROMATIC COMPOUNDS. 


ALCOHOLS, C,H,.0,H,O, AND 
KETONES, (©,H,.C,H,0. 


2455 Methylstyrolylcarbinol, C,H,.C,H,.CH(OH)CH,, is formed 
by the action of sodium amalgam on an alcoholic solution of 
acetocinnamone, C,H, CHARGE: CO.CH,, and forms a crystalline 
mass, melting at 68°. 

Methylstyrolylketone, C,H,.C,H,.CO.CH,, is obtained by boiling 
benzylaceto-acetic ether with alcoholic potash? and also by the 
distillation of the calcium salts of hydrocinnamic and acetic 
acids* It is an aromatic smelling liquid, which boils at 
235°—256°, readily combines with acid sulphites of the alkalis 
and is converted by oxidation into benzoic acid. 

Hithylbenzylketone, C,H;.CH,.CO.C,H,, has been prepared from 
phenylacetyl chloride and zine ethyl. It boils at 225°—226°, 
does not combine with the acid sulphites of the alkalis and 
yields propionic and benzoic acids on oxidation.‘ 

Propylphenylketone, C,H;.CO.C,H,, is formed when calcium 
butyrate and benzoate are heated together,® and is also obtained 
by the action of aluminium chloride on a mixture of benzene 
and butyryl chloride® It is a pleasant smelling liquid, which 
boils at 220°—222°, does not form an alkali sulphite-compound 
and is also oxidized to eats and benzoic acids by chromic 
acid. 

Lsopropylphenylketone, C,H,.CO.CH(CH,),, boils at 209°—217° 


and yields acetone and benzoic acids as oxidation products.’ 


PHENYLBUTYRIC ACIDS. 
2456 Phenylbutyric acid, C,H;.CH,.CH,.CH,.CO,H, is formed 


by the continued action of an excess of sodium amalgam ona hot 
solution of phenylisocrotonic acid, C,H,.CH—CH.CH,.CO,H, 
kept neutral by the addition of sulphuric acid. It boils at about 


1 Engler and Leist, Ber. Deutsch. Chem. Gres. vi. 254. 
2 Ehriich, Ann. Chem. Pharm. clxxxvii. 11. 

~) Jackson, Ber. Deutsch. Chem. Ges. xiv. 889. 

4 Popow, ibid. v. 500. 

> Schmidt and Fieberg, zbid. vi. 498. 

6 Bureker, Bull. Soc. Chim. xxxvii. 4. 

7 Popow, Ber. Deutsch. Chem. Ges. vi. 1255. 


PHENYLHYDROXYBUTYRIC ACIDS. 321 





290°, crystallizes from hot water in long, flat plates, resembling 
those of benzoic acid, and melts at 47°5°.4 

Phenylisobutyric acid or Methylbenzylacetic acid, C,H,.CH,.CH 
(CH,)CO,H, is obtained by heating benzylmethylaceto-acetic 
ether with concentrated caustic potash, as well as by heating 
methylbenzylmalonic acid, CH,.C(CH,C,H;)(CO,H),; it is also 
formed by the combination of hydrogen with phenylcrotonic 
acid,? C,H,.CH—C(CH,)CO,H. It crystallizes in plates, is only 
slightly soluble in cold water, melts at 37° and boils at 272°. 
When its ammonium salt is heated to 280°, phenylisobutyramide 
is formed ; it crystallizes in needles, melting at 109°. 


PHENYLHYDROXYBUTYRIC ACIDS. 


2457 LPhenylhydroxybutyric acid, C,H,.;CH(OH)CH,.CH,. 
CO,H. The phenylisocrotonic acid, which is mentioned 
above, combines with hydrobromic acid to form phenylbromo- 
butyric acid, which is converted by a dilute solution of sodium 
carbonate or by boiling with water into phenylbutyrolactone 

CH,.CH, 
C,H;.CH | , which crystallizes from alcohol in long, 
\o—co 


flat needles and from carbon disulphide in splendid, six-sided, 
rhombic tablets, has an aromatic odour, melts at 37° and boils 
at 306°, but readily sublimes at 100° If it be boiled with 
baryta water, the solution well-cooled with ice and then treated 
with hydrochloric acid, phenylhydroxybutyric acid is precipi- 
tated. . The free acid separates from carbon disulphide in flat, 
transparent crystals, which decompose on heating into water | 
and the lactone (Fittig and Jayne). 

Phenylhydroxyisobutyric acid or Benzylmethylglycolic acid, 
O,H,.CH,.C(CH,)(OH)CO,H, was obtained by Gabriel and 
Michael by heating the hydrogen sodium sulphite compound of 
benzylmethylketone in closed vessels with potassium cyanide and 
alcohol and boiling the solution thus obtained with hydrochloric 
acid. It crystallizes from benzene in long prisms, which melt at 
97°—99° and are readily soluble in hot water and alcohol. 

1 Fittig and Jayne, Ann. Chem. Pharm. ccxvi. 107. 

2 Conrad and Bischoff, 7bid. cciv. 177; Edeleano, Ber. Deutsch. Chem. Ges. 


Sx GLG, 
3 Ber. Deutsch. Chem. Ges. xii. 814. 


322 AROMATIC COMPOUNDS. 


KETONIC ACIDS, C,,H,,0,. 


2458 Benzoylpropionaldehyde, CO,H;.CO.CH,CH,.CHO, is 
formed when the compound of propylphenylketone with chromyl 
chloride (Pt. IV. p. 6) is decomposed with water. It is an 
aromatic smelling liquid, which boils at about 235° and readily 
oxidizes to the following compound.! 

Benzoylpropionie acid, C,H;.CO.CH,.CH,.CO,H, is the cor- 
responding ketonic acid to the above aldehyde and is formed 
when a mixture of benzene and succinic anhydride is heated with 
aluminium chloride,? as well as by heating benzoylisosuccinic 
acid,> C,H,CO.C,H;.(CO,H),. It crystallizes from hot water m 
flat, lustrous needles or plates, which melt at 116° and when 
more strongly heated are partially converted into a red substance 
and partly sublime. The action of sodium amalgam on its 
alkaline solution reduces it to phenylbutyrolactone. Its phenyl- 
hydrazone crystallizes in silky needles, which soon change into 
a yellow resinous mass. 


BENZOYLACETONE AND 
BENZOYLPYRORACEMIC ACID. 


2459 Benzoylacetone, C,H;.CO.CH,.CO.CH,, is formed, to- 
gether with acetophenone and benzoic acid, when benzoylacetic 
acid is boiled with water.* It is also a product of the action of 
sodium ethylate on a mixture of acetone and ethyl benzoate,® 
but it is best prepared by covering sodium ethylate, free from 
alcohol, with an excess of acetic ether and gradually adding the 
calculated quantity of acetophenone, the liquid being cooled 
with ice. The liquid product solidifies after a short time to a 
thick mass of light yellow crystals of sodium benzoylacetone : 


C,H,.ONa + C,H,.CO.CH, + C,H,.0CO.CH, = 
C,H,.CO.CHNa.CO.CH, + 2C,H,.OH. 


1 Burcker, Compt. Rend. xciv. 220. 

? Burcker, Bull. Soc. Chim.’ xxxv. 17; Pechmann, Ber. Deutsch. Chem. Ges. 
xv. 889. 

* Kues and Paal, ibid. xviii. 3323 ; see also Bischoff, ibid. xix. 95. 

* Fischer and Kuzel, <bid, xvi. 2289 ; Fischer and Biilow, <bid. xviii. 2131. 

5 Claisen, ibid. xx. 655. 


BENZOYLACETONE. 323 


The mass is triturated with ether and filtered, the residue being 
dissolved in water and decomposed with acetic acid, which 
precipitates the benzoylacetone in the form of small prisms.* 

This substance melts at 60°—61°, boils almost without de- 
composition at 260°—262° and is readily volatile with steam. 
It has a very pleasant, penetrating odour, is only slightly soluble 
in cold, more readily in hot water and is readily soluble in 
alcohol and caustic soda solution. It gives an intense claret-red 
colouration with ferric chloride and is decomposed by boiling 
with alkalis into acetic acid and acetophenone. 

Silver benzoylacetone, C,H;.CO.CHAg.CO.CH,, is a white, crys- 
talline precipitate, which is formed by the addition of silver 
nitrate to a solution of the ketone in ammonia. 

Copper benzoylacetone, (C,,H,O,),Cu, is obtained by mixing 
alcoholic solutions of the ketone and copper acetate; it is a 
pale green precipitate, which crystallizes from hot alcohol in 
light green needles. 

Benzoylacetonamine, C, .H,)(NH)O, is readily formed when the 
ketone is added to alcoholic ammonia; it is gradually deposited 
in strongly lustrous, transparent, rhombic crystals, which melt 
at 143° and volatilize without decomposition. It dissolves without 
alteration in cold mineral acids, but is decomposed, if these 
solutions be boiled, into ammonia and benzoylacetone. 

Benzoylacetoxime, C,)H,,(NOH)O, is obtained by heating an 
alcoholic solution of benzoylacetone with an excess of hydroxyl- 
amine hydrochloride for 3—4 hours. It separates out on 
the addition of water and crystallizes from alcohol in lustrous 
scales, which melt at 65°5°—66°, have a characteristic, not un- 
pleasant odour, a sharp taste and are volatile with steam.” 

Isonitrosobenzoylacetone, C,H;.CO.C(NOH)CO.CH,, is formed 
when a molecule of the ketone is added to an alcoholic solution 
of one atom of sodium, and nitrogen trioxide passed into the well- 
cooled solution until it has a neutral reaction. A mixture of 
the ketone with benzoic acid is precipitated by the addition of 
water, the latter being removed by means of dilute caustic soda. 
The isonitrosobenzoylacetone is then recrystallized from hot water, 
from which it separates in long, pure white needles, which melt 
at 123°5°—124° and form a yellow solution in alkalis (Ceresole). 

Benzoylpyroracemic acid, C,H,.CO.CH,.CO.CO,H. When an 
alcoholic solution of sodium is well cooled with ice and treated 


1 Claisen and Beyer, Ber. Deutsch. Chem. Ges. xx. 2078. 
2 Ceresole, ibid. xvii. 812. 


324 AROMATIC COMPOUNDS. 


with acetophenone and ethyl oxalate in the proportions required 
by the following equation, the sodium compound of the ethyl 
ether of this acid is formed: 


C.H,.CO.CH, + C,H,0.CO.CO.00,H, + C,H,.ONa = 
C.H,.CO.CHNa.CO.CO.0C,H, + 2C,H,.OH. 


If more sodium ethylate than this be employed, however, a 
crystalline precipitate is formed, which yields benzoylpyroracemic 
acid on decomposition with hydrochloric acid. This acid crys- 
tallizes from benzene in yellowish white prisms, which melt at 
155°—156° and decompose at a slightly higher temperature with 
evolution of carbon dioxide. 

Lthyl benzoyl-pyroracemate, C,H,.CO.CH,.CO.CO,.C,H,. When 
the sodium compound mentioned above is dissolved in ice-water 
and a current of carbon dioxide passed through the solution, 
the ether is precipitated. It crystallizes from petroleum-spirit 
in splendid prisms, which melt at 43°. Its alcoholic solution 
gives a blood-red colouration with ferric chloride and with copper 
acetate a precipitate of the copper compound, (C,,H,,0,),Cu, 
which crystallizes from hot alcohol in fine, light green needles. 
The ether is decomposed into acetophenone, alcohol and oxalic 
acid by hot, dilute caustic soda; alcoholic ammonia acts in a 
similar manner, oxamide being in this case the product.? 


DIBASIC ACIDS, C,H,.C,H,(CO,H),. 


2460 Phenylsuccinic acid, C,H,.CH(CO,H)CH,.CO,H, was first 
obtained by Riigheimer, who prepared the nitril, C,H,.CH(CN) 
CH,.CN, by heating @-phenylchlorethylene, C,H,.CCl = CH,, 
to 200°—220° with potassium cyanide, and_decomposing it by 
boiling with baryta water. He then obtained it im larger 
quantity by the action of ethyl phenylbromacetate on sodaceto- 
acetic ether and subsequent hydrolysis of the phenylacetosuccinic 
ether with potash :? 

CH,.CO.CH.CO,.C,H, 
| + 3KOH = 
Ce UEGOAC si: 
CH,.CO,K 


| 
C,H,.CH.CO,K 


} Beyer and Claisen, Ber. Deutsch. Chem. Ges. xx. 2181. 
2 Ber. Deutsch. Chem. Ges, xiv. 428. 


+ OH,.CO.OK + 2H0.C,H,,. 


PHENYLSUCCINIC ACID. 325 








Spiegel then found that it is also formed, together with toluene, 
when dihydrocornicularic acid, C,H,.CH(CO,H)CH,.CO.CH, 
C,H,, is fused with caustic potash, and prepared it synthetically 
by acting upon sodium ethyl malonate with ethyl phenylchlor- 
acetate, hydrolysing the ether and heating the phenylcarboxyl- 
succinic acid thus obtained :? 


OOH | 
CHC ‘ CH,.CO,H 


+ CO,. 

C,H,;CH—CO,H C,H,.CH.CO,H 
Phenylsuccinic acid crystallizes from hot water in stellate groups 
of short needles, which are readily soluble in alcohol and melt 
at 167°. 

Calcium phenylsuccinate, C,,H,O,Ca, is precipitated even from 
a dilute solution of the ammonium salt by boiling it with calctum 
chloride. It is thus deposited as a crystalline powder, while it 
separates in the cold in crystals containing two molecules of 
water. | 

Phenylsuccinic anhydride, C;H;C,H,(CO),0, is formed by 
heating the acid alone or with acetic anhydride and solidifies 
on cooling to a tough, crystalline mass, which melts between 
45°—50°. 

Phenylrsosuccinie acid, OC,H;.CH,CH(CO,H),. The ethyl 
ether of this acid, which is also known as benzylmalonic acid, is 
obtained by the action of benzyl chloride on sodium ethyl 
malonate, as a faintly aromatic smelling liquid, which boils at 
300°. The free acid is readily soluble in water and alcohol and 
forms asymmetric crystals, which have an aromatic odour, melt 
at 117° and decompose into carbon dioxide and hydrocinnanic 
acid when more strongly heated.? 

Benzyltartronie acid, C,H;.CH,.C(OH)(CO,H),. The ether of 
benzylchloromalonic acid is formed by the action of benzyl- 
chloride on sodium chloromalonic ether and is converted by 
caustic potash into benzyltartronic acid. This substance is 
readily soluble in water and alcohol and crystallizes in lustrous 
prisms, which melt at 143° and decompose on further heating into 
carbon dioxide and a-phenyl-lactic acid.° 


1 Ber. Deutsch. Chem. Ges. xiv. 873; Ann, Chem. Pharm. cexix. 29. 
2 Conrad, zbid. eciv. 174. 
3 Ibid. ccix. 2438. 


326 AROMATIC COMPOUNDS. 


Cinnamic acid is always formed ‘in addition to the benzyltar- 
tronic acid by the action of potash or baryta:? 


C,H,.CH,.CCl(CO,H), = C,H,;,CH—CH.CO,H + CO, + HCl. 


Benzoylcyanacetic acid, C,H;.CO.CH(CN)CO,H. The ethyl 
ether of this acid is formed when a mixture of ethyl benzoyl- 
acetate and an alcoholic solution of sodium ethylate is saturated 
with cyanogen chloride. It is readily soluble in alcohol and 
alkalis and forms crystals, melting at 37°5°. On boiling with 
water, it decomposes with formation of cyanacetophcnone.” 


PHENYLBUTYLENES OR BUTENYLBENZENES. 


2461 These bodies have not yet been fully investigated. 
Phenyl-a-butylene, C,H;.CH—CH.CH,.CH,, was prepared by 
Perkin from hydrocinnamenylacrylic acid, C,H,.CH—CH.CH,. 
CH,.CO,H, by elimination of carbon dioxide. It is a liquid, which 
has a similar smell to styrolene, boils at 186°—187° and forms a 
dibromide, which crystallizes from alcohol in needles, melting at 
67°. This hydrocarbon is undoubtedly identical with that which 
Radziszewski obtained by treating boiling butylbenzene with 
bromine and submitting the sehate to distillation.* 
Para-a-butenylphenyl methyl ether, C,H,(OCH,)C,H,, is formed 
when methylparahydroxyphenylangelic acid is distilled and is a 
well-crystallized substance, which has an odour resembling that 
of anethol (p. 196), melts at 17° and boils at 242°—245° 
Phenyl-B-butylene, C,H,.CH,.CH—CH.CH,, was obtained by 
Aronheim by the action of sodium on a mixture of benzyl 
chloride and allyl iodide, an intermolecular change taking place 
just as in the formation of B-butylene from methyl iodide and 
allyl iodide (Pt. IIL p. 164).© It is also a product of the dry dis- 
tillation of phenylhomoparaconic acid,’ C,,H,,O,, and is a liquid, 
boiling at 176°—177°. It forms a liquid dibromide, which decom- 


1 Ann. Chem. Pharm. ccix. 241. 

2 Haller, Compt. Rend. ci. 1270. 

3 Jowrn. Chem. Soc. 1877, ii. 667. 

4 Ber. Deutsch. Chem. Ges. ix. 260. 

5 Perkin, Journ. Chem. Soc. 1877, ii. 661. 
6 Ann. Chem. Pharm. clxxi. 225. 

7 Penfield, 2bid, cexvi. 124. 


PHENYLBUTYLENES. (TSS Se 


poses on heating and yields naphthalene, C,,H,, the formation of 
which can readily be understood, when passed over heated lime 
(Pt. IIT. p. 38). 

Phenylisobutylene, C,H;.CH—C(CH,),, was prepared by Perkin 
from benzaldehyde, sodium isobutyrate and isobutyric anhydride.* 
Phenylhydroxypivalic acid, C;H;.CH(OH)C(CH,),CO,H, is the 
first product and then decomposes into water, carbon dioxide and 
phenylisobutylene This hydrocarbon is a liquid, boiling at 
184°—186°, which is oxidized by chromic acid to benzoic and 
acetic acids. It forms a liquid dibromide, which is converted by 
alcoholic potash into phenylbromisobutylene, C,H , CU Br-—O(CH,).. 

This liquid combines with bromine to ee phenylbromiso- 
butylene dibromide, C,H ;.CBr,.CBr(CH,),, which crystallizes from 
acetic acid in plates, which resemble those. of sublimed benzoic 
acid and melt at 63°5°. 

Ortho-isobutenylphenol, C,H ,(OH)C,H,, is formed when salicyl- 
aldehyde is heated with isobutyric anhydride and sodium 
isobutyrate : 


C,H ga ee o4 

‘Non * Noo. CH(CH,), 

(GA Ganon OC OH gE 

OH, A (CH3), 
OH 


CO. CERO sy » 


+ CO, + HO.CO.CH(CH,).. 


The product consists of the isobutyric ether of the phenol, 
which is readily hydrolysed. Ortho-isobutenylphenol is a colour- 
less liquid, which smells simultaneously of smoke and cedar wood 
and boils at 223°—225° 

Para-isobutenylphenol, which has been prepared from para- 
hydroxybenzaldehyde, boils at 230°— 235° and_ solidifies to 
crystals in a freezing mixture. Its methyl ether is formed in a 
similar manner from anisaldehyde. It smells like anethol, boils 
at 236°—287° and solidifies in the cold to crystals, melting at 9°3 

Phenylbutylene alcohol, C,H;.CH(OH)CH,.CH,.CH,.OH, is 
formed by the action of sodium amalgam on a dilute alcoholic 
solution of benzoylpropionaldehyde and is a thick liquid, which 
boils at about 200° and is reconverted into the aldehyde by 


oxidation.* 
1 Journ, Chem. Soc. 1879, i. 141. 
2 Fittig and Jayne, Ann. Chem. Pharm. ccxvi. 119. 
3 Perkin, Journ. Chem Soc. 1879, i. 142. 
4 Burcker, Compt. Rend. xciv. 220. 


287 


328 AROMATIC COMPOUNDS. 


PHENYLCROTONIC ACIDS. 


2462 Phenylmethylacrylaldehyde, C,H,.CH—C(CH,)CHO, is 
obtained when equal molecules of benzaldehyde and: propion- 
aldehyde are dissolved im alcohol and treated with dilute caustic 
soda : 


CH 


\cHO 


O,H,.CHO + C 
\ CHO 


= C,H,.CH=C + H,0. 


It is a liquid, which smells like cinnamaldehyde, combines 
with acid sodium sulphite and phenylhydrazine and is con- 
verted into the acid by boiling with silver oxide and dilute 
alcohol.* 

Phenylmethylacrylic acid, C,H ,.CH—C(CH,)CO,H, which was 
termed phenylcrotonic acid by Perkin, is formed when benz- 
aldehyde is heated with propionic anhydride and sodium 
propionate,” or with acetic anhydride and sodium propionate? 
and is most simply prepared by heating benzidene chloride for 
8—10 hours to 150° with an excess of sodium propionate 4 
(p. 212). 

It is also obtained, together with the benzyl ether of phenyl- 
isobutyric acid, toluene and propionic acid, by the action of 
sodium on benzyl propionate :° 


CH, GH ei GH: 
| | | 

2 CH, +2Na=CH, + C—CH.C,H,+CH,.0,H,+H,.. 
| | | 

CO,.CH,,.C,H; CO,Na CO,Na 


It is slightly soluble in water, readily in alcohol, ether or 
benzene, and crystallizes in needles or short, oblique prisms, 
melting at 78°. If its solution im chloroform be treated with 
petroleum-spirit and a few drops of water, it separates upon 
evaporation of the chloroform in diamond-lustrous needles, 
which probably contain water (Erdmann). It is only slowly 

1 Miller and Kinkelin, Ber. Deutsch. Chem. Ges. xix. 525 and 1248. 

2 Journ. Chem. Soc. 1877, i. 391 and ii. 660 ; Conrad and Bischoff, Ann. Chem. 
Pharm. eciv. 188. 

3 Fittig and Slocum, 7did. cexxvii. 228. 


* Erdmann, bid. ecxxvil. 247. 
5 Conrad and Hodgkinson, ibid. exciii. 314 ; Conrad and Bischoff, loc. cit. 


PHENYLCROTONIC ACIDS. 329 





volatile with steam and boils at 288°. On heating with a 
mixture of four volumes of sulphuric acid and six volumes of 
water, it is converted into methronene, C,,H,, an aromatic smelling 
liquid, which boils at 322°—323°. 

This substance, which will be subsequently described, has the 
following. constitution : 


CH(C,H,)CH.CH, 
ARG < 
PACH =sQE tls 


Phenylisocrotonic acid, C,H,.CH—CH.CH,.CO,H, was obtained 
by Perkin, who named it ¢sophenylerotonic acid, by heating 
benzaldehyde with succinic anhydride and sodium succinate.1 
Fittig and Jayne have found that the chief product of the 
reaction is phenylparaconic acid, phenylisocrotonic acid being a 
decomposition product of this.” 

The reaction proceeds in the following manner : 

Benzaldehyde and sodium succinate combine, in a manner 
similar to that which occurs in the formation of aldol (Pt. I. 
p. 168), to form sodium phenylitamalate : 


COONa COONa 
| 
C,H,CHO + CH,.CH, = C,H,.CH(OH).CH—CH, 
| 
CO.ONa CO.0ONa 


The phenylitamalic acid, however, decomposes immediately 
into water and phenylparaconic acid, which is simultaneously a 
lactone : 


CO.OH CO.OH 
| | 
C.H,.CH—CH—CH, =C,H,.CH.CH.CH, +H,0. 
| 
OH CO.OH OF22460 


This is then decomposed by heating into carbon dioxide and 
phenylisocrotonic acid, which is, therefore, most readily prepared 
from phenylparaconic acid : 





CO,H 
| 
C.H,.CH.CH.CH, = ee He COR 
| 
ee CO CO.OH 


1 Journ. Chem. Soc. 1877, i. 895. 2 Ann. Chem. Pharm. cexvi. 97. 


330 AROMATIC COMPOUNDS. 


A small quantity of the isomeric phenylbutyrolactone (Pt. IT. 
p. 168) and a little a-naphthol, C,,H,(OH), are simultaneously 
formed.* 

Phenylisocrotonic acid is scarcely soluble in cold, only slightly 
in boiling water, from which it crystallizes in lon, thin needles, 
while it separates from carbon disulphide, in which it is more 
readily soluble, in short, prismatic crystals. It melts at 86° and 
boils at 302°, almost without decomposition. On boiling with 
dilute sulphuric acid, it is converted into phenylbutyrolactone.? 
Other unsaturated acids are also converted into their lactones in 
this way, the reaction corresponding exactly to the formation of 
alcohols from olefines, ¢.g. that of trimethylcarbinol from isobu- 
tylene. Hydroxy-acids are first formed by the assumption of 
the elements of water, phenylhydroxybutyric acid being formed 
in the case under consideration, and then immediately decom- 
pose into the lactone and water, provided that the hydroxyl has 
taken the y-position (Fittig) : 


C,H,.CH—CH.CH, C,H,.CH.CH,.CH, 
| + H,0 = x 
CO.OH OH  CO.OH 
C.H,.CH.CH,.CH, 
+ H,0. 
O CO 





Phenyl-a-crotonie acid or Methylatropic acid is formed when 
sodium phenylacetate is heated with paraldehyde and acetic 
anhydride : 

ZOHCH, 
C,H,.CH,.CO,H + COH.CH, = OH. CC + H,0. 
: : CO,H 


It crystallizes from hot water in small prisms, melting at 135°. 

Phenyl-a-hydroxyisocrotonic acid, CO,H,.CH—CH.CH(OH) 
CO,H. The nitril of this acid is obtained when cinnamaldehyde 
is dissolved in a little ether, rather more than the equivalent 
amount of potassium cyanide added, and concentrated hydro- 
chloric acid then gradually run into the cooled liquid ;* it is 
also formed when a mixture of oil of cinnamon and anhydrous 


1 Fittig and Erdmann, Ann. Chem. Pharm. cexxvii. 242. 

2 Erdmann, bid. eexxvii. 257. 

3 Ogliarolo, Gaz. Chim. Ital. xv. 514. 

4 Matsmoto, Ber. Dewtsch. Chem. Ges. viii. 1145; Peine, ibid. xvii. 21138. 


PROPIONCOUMARIN. 331 


hydrocyanic acid is allowed to stand.! It forms white, granular 
crystals, melts at 80°—81° and is converted by boiling with 
dilute hydrochloric acid into the acid, which crystallizes from 
hot water in long, flat needles, melting at 115°—116°. 


HXDROXYPHENYLCROTONIC ACIDS. 


O——CO 
2463 Propioncoumarin, CoH >CH, is prepared by 
GCHesUE: 


heating sodium salicylaldehyde with propionic anhydride and 
forms rhombic crystals, which smell like coumarin and melt at 
90°. It boils at 292°5° and yields salicylic acid on fusion with 
potash, propioncoumaric acid being first formed. Its derivatives 
resemble those of coumarin and, like this, it yields two series of 
‘substituted propioncoumaric acids. 

a-Methylpropioncoumaric acid, C,H,(OCH,)C,H,.CO,H, forms 
monosymmetric crystals, melting at 118°, which are reconverted 
into propioncoumarin by sulphuric acid. 

8-Methylpropioncoumarie acid also crystallizes in the monosym- 
metric system, melts at 107° and is converted by sulphuric acid 
into a thick, oily liquid.? 

Methylpropionparacoumarre acid was obtained by Perkin, who 
heated anisaldehyde with sodium propionate and propionic 
anhydride. It crystallizes from alcohol in rectangular tablets, 
which melt at 154° and decompose into carbon dioxide and 
anethol when more strongly heated.* 

B-Methyleoumarin, C, ,H,O,, is formed by the action of concen- 
trated sulphuric acid on a mixture of phenol and aceto-acetic ether: 


CO.0C,H, 


ou | 
CHK + pees - 


CH, 


CHK | +H,0+H0.G.H,. 
Gat 

| 

CH, 


1 Pinner, Ber. Deutsch. Chem. Ges, xvii. 2010. 
2 Perkin, Jowrn. Chem. Soc. 1875, x. ; 1881, i, 409. 
8 Ibid. 1877, i. 411. 


332 AROMATIC COMPOUNDS. 


This substance is very similar to coumarin and crystallizes 
from benzene in needles which melt at 125°—126°1 

Methyleoumarilic acid, C,H,.C,O0(CH,)CO,H- When 
phenoxylacetoacetic ether, obtained by the action of sodium 
phenate on chloracetoacetic ether, is treated with concentrated 
sulphuric acid, the ethyl ether of methylcoumarilic acid 1s 
formed : 


O O 

CH Oat x CHC | 0.00, 0,H, +H,0. 
J 
| | 
CH, CH; 

This body crystallizes from benzene in large, rhombic tablets, 
melts at 51°, boils at 290° and is readily saponified by alkalis. 
The free acid crystallizes from alcohol on gradual evaporation in 
small, lustrous prisms, which sublime when carefully heated, 
but melt at 188°—189° when rapidly heated and simultaneously 
decompose into carbon dioxide and methylcoumar on (p. 247), 
which has the following constitution : 


CC cu. 
DN er a 
| 
CH, 
This boils at the melting point of the acid and is a liquid 


which possesses an odour similar to that of naphthalene but 
more agreeable.” 


DIHYDROXYPHENYLCROTONIC ACIDS. 
2464 Homoferulic acid, C,H,(OH)(OCH,)CH—C(CH,)CO,H. 


Propionhomoferulic acid is formed when vanillin is heated 
with sodium propionate and propionic anhydride : 


/ OCH, 
C,H, OH i 2CH,.CH,.CO,H = 
*\ CHO 


// OOH, 
C,H, 0.00, Grains aE. 
*\CH=C(CH,)CO,H 


1 Pechmann and Duisberg, Ber, Deutsch. Chem. Ges, xvi. 2127. 
* Hantzsch, ibid. xix. 1290. 


HOMOFERULIC ACIDS. 333 





It crystallizes from alcohol in needles, which melt at 128°— 
129°, and is converted by boiling with dilute caustic soda into 
homoferulic acid, which crystallizes from boiling water in flat 
needles, melts at 167°—168° and is resolved into iso-eugenol 
(p. 199) and carbon dioxide by heating with lime. It is con- 
verted by the action of sodium amalgam and water into hydro- 
homoferulic acid, which separates from hot water in crystals, 
melting at 114°—115°. 

Methythomoferulic acid or Dimethylhomocaffeic acid,C,H,(OCH,), 
CH—C(CH,)CO,H, is obtained by the methylation of homo- 
ferulic acid and crystallizes in pointed needles, which melt at 
140°—141°2 

. O——-—CO 
8-Methylumbelliferon, HO.0,H,Z | y» as . formed 

\C(CH,) : CH 
when a mixture of equal molecules of resorcinol and aceto- 
acetic ether is brought into five times the amount of concen- 
trated sulphuric acid, It crystallizes from hot water in lustrous 
needles and from alcohol in aggregates of prisms, which melt at 
185° and sublime in small plates, when carefully heated. It 
forms a yellow solution in dilute alkalis, which shows a blue 
fluorescence, and this fluorescence is also shown by its colourless 
solution in sulphuric acid. Small quantities of resorcinol can 
therefore be detected by adding a little aceto-acetic ether and 
cold sulphuric acid. 

On fusion with potash, resacetophenone C,H,(OH),CO.CH,, 
(p. 60) is formed.” 

Nitro-B-methylumbelliferon, C,,H(NO,)O;, is obtained by 
gradually adding the calculated quantity of concentrated nitric 
acid to glacial acetic acid containing finely divided @-methylum- 
belliferon in suspension. It crystallizes from boiling glacial 
acetic acid in straw-yellow needles. 

Amido-B-methylumbelliferon, C,,H,(NH,)O3, is formed by the 
reduction of the nitro-compound with tin and hydrochloric acid 
and crystallizes from hot water in yellowish needles, which melt 
at 247° and form a yellow solution in alkalis. The solution in 
concentrated sulphuric acid has a blue fluorescence, and its 
alcoholic solution gives an intense green colouration with ferric 
chloride. If it be dissolved in dilute sulphuric acid and treated 
with sodium nitrite, nitroso-amido-B-methylumbelliferon, C,H, 


1. Kraaz and Tiemann, Ber. Deutsch. Chem. Ges. xv. 2059, 2070. 
2 Pechmann and Duisberg, xvi. 2119. 


334 AROMATIC COMPOUNDS. 


(NO)(NH,)O,,is formed. This body crystallizes in yellowish red 
needles, forms a deep red solution in alkalis and gives 
Liebermann's reaction. 

B-Methylumbellic acid, (HO),C,H,.C(CH,)—CH.CO,H. When 
the calculated quantities of sodium and methylumbelliferon are 
dissolved in methyl] alcohol and the solution heated with methyl 
iodide, the methyl ether of @-methylumbelliferon is formed. 
This is a crystalline substance, which melts at 159° and forms a 
solution in sulphuric acid, which shows a deep blue fluorescence. 
On boiling with caustic potash solution of 50 per cent., it is 
converted into methyl-B-methylumbellic acid, (CH,0)(OH)C,Hs,. 
C(CH,)—CH.CO,H, which is insoluble in water and crystallizes 
from methyl alcohol in strongly refractive, four-sided tablets, 
which melt at 140° with evolution of carbon dioxide. On 
boiling with dilute acids it is reconverted into @-methylumbelli- 
feron and this change is also brought about by heating with 
dilute ammonia (Pechmann and Duisberg). It decomposes on 
distillation into carbon dioxide and allylresorcinol methyl ether 
(Pechmann and Cohen), 

Dimethyl-B-methylumbellic acid, (CH,0),C,H,C(CH,)—CH. 
CO,H. The methyl ether of this acid is obtained by heating a 
solution of sodium and the monomethyl-compound in wood- 
spirit with methyl iodide. It is an oily liquid boiling at 310°— 
320°. The free acid crystallizes from dilute alcohol in small 
needles, which melt at 145°. It is oxidized by potassium per- 
manganate to dimethyl-8-resorcylic acid (Pechmann and Cohen). 

Metahydroxymethyleoumarilic acid, 2C,H,(OH)C,0(CH,)CO,H 
+H,O. The ethyl ether of this substance is formed when 
resorcinol and chloracetoacetic ether are boiled with an alcoholic 
solution of sodium. It crystallizes in needles which form blue 
fluorescent solutions in ether and the alkalis. This fluorescence 
disappears when the alkaline solution is boiled, the acid being 
formed. The latter crystallizes from hot water in needles, which 
become anhydrous at 110°, melt at 226° with evolution of carbon 
dioxide and decompose when more rapidly heated into carbon 
dioxide and hydroxymethylcoumaron, which slightly resembles 
naphthol in odour and crystallizes from hot water in needles, 
which melt at 96°—97° and become coloured green in the air. 

All these compounds. give violet colourations on heating with 
sulphuric acid.? 


1 Pechmann and Cohen, Ber. Deutsch. Chem. Ges. xvii. 2129. 
2 Hantzsch, ibid. xix. 2927. 


TRIHYDROXYPHENYLCROTONIC ACIDS. 335 


TRIHYDROXYPHENYLCROTONIC ACIDS. 


2465 v-Dihydroxy-B-methylcoumarin or B-Methyldaphnetin, 


CO 

(HO),CHAC De 

C(CH,):CH 
and aceto-acetic ether and crystallizes from hot water in needles, 
which melt at 235°, Its solution in dilute alcohol gives an 
intense green colouration with ferric chloride. It forms a 
yellow non-fluorescent solution in alkalis and its solution in 
sulphuric acid is also non-fluorescent! If it be boiled with 
sodium bisulphite solution until complete solution has taken 
place and be then treated with ferric chloride, the liquid is 
coloured deep blue, while ammonia and potassium ferricyanide 
produce a reddish yellow colouration? (p. 255). 

a-Dihydroxy-B-methylcoumarin has been prepared from 
phloroglucinol and crystallizes from alcohol in needles, which melt 
at, 282°—284°. The alkaline solution is also non-fluorescent and 
the compound is therefore probably not the true homologue of 
aesculetin (p. 256) (Pechmann and Cohen). 

Dihydroxymethyleumarilic acid, 2C,H,(OH),C,0(CH,)CO,H+ 
H,O, has also been prepared from phloroglucinol. It forms 
erystals, which become anhydrous at 120° and melt at 281° with 
decomposition. When it or its ether is heated with concen- 
trated sulphuric acid, an indigo-blue solution is obtained.’ 

Scopoletin, C,,H,O,, is a constituent of the root of Scopolia 
japonia, the Japanese Belladonna,* and. is, according to 
Paschkis,® identical with the “Schillerstoff” of the deadly 
nightshade (Atropa Belladonna), which was termed chrysatropic 
acid by Kunz.° 

Scopoletin crystallizes from alcohol in needles, which are 
only slightly soluble in cold, rather more readily in hot water, 
melt at 198° and sublime when more strongly heated. Its 
solution has a faint acid reaction and shows a blue fluorescence, 





has been prepared from pyrogallol 


1 Pechmann and Duisberg, Ber. Deutsch. Chem. Ges. xvi. 2127. 

? Pechmann and Cohen, ibid. xvil. 2189. 

3 Lang, ibid. xix. 2934, 4 Kijkman, 7bid. xvii. Ref. 442, 
5 Ibid. xix. Ref. 305. 8 Tbid. xix. Ref. 104, 


336 AROMATIC COMPOUNDS. 


Scopolin, C,,H,,0,,+2H,O, occurs together with scopoletin and 
crystallizes in needles, which melt at 218°. On continued 
boiling with dilute sulphuric acid it decomposes into scopoletin 
and glucose : 


C,H 39015 + 2H,O a C,,H,,9; i 20H .0¢. 


The root also contains scopolein, a poisonous substance, which 
is closely related to atropine. 


KETONES ©,,H,,0 


2466 Benzalacetone or Acetocinnamone, C,H,.C,H,.CO.CHg, is 
formed in small amount, together with other products by the 
distillation of a mixture of calcium acetate and calcium 
cinnamate + and is also formed when benzaldehyde and acetone 
are heated with acetic anhydride and zinc chloride for some 
time” It may however be much more conveniently prepared 
by the action of very dilute caustic soda on an aqueous solution 
of benzaldehyde and acetone :? 


C,H,.CHO + CH,.CO.CH, = C,H,.CH—CH.CO.CH, + H,0. 


It crystallizes in lustrous, thick, quadratic tablets, melts at 
41°—42°, boils at 260°—262° and possesses an odour which 
resembles those of coumarin and rhubarb. Applied to sensitive 
portions of the skin, it produces an unpleasant burning and 
itching sensation. It combines with bromine to form methyl- 
dibromostyrolylketone, C,H,.CHBr.CHBr.CO.CH,, which crys- 
tallizes from alcohol in short needles, and melts at 124°—125° 
with decomposition. | 


KETONES, C,,H,,0,. 


2467 Methylcowmarylketone, C,H ,(OH)CH—CHCO.CH,. When 
an aqueous solution of helicin (Pt. IV. p. 288) is heated with 
acetone and dilute caustic soda solution, glucomethylcoumarylke- 


tone, C,H,(O.C,H,,0,)C,H,.CO.CH,, is formed. This crystallizes 


1 Engler and Leist, Ber. Deutsch. Chem. Ges. vi. 254. 
2 Claisen and Claparede, zbid. xiv. 2461. 
3 Claisen and Ponder, Ann. Chem. Pharm. cexxili. 137. 


CINNAMYLFORMIC ACID. 337 


from hot water in yellowish needles, which melt at 192° and 
are converted by emulsin into methylcoumarylketone, which 
crystallizes from alcohol in long, white needles, melting at 
130% 

Methylferuloketone, C,H,(OH)(OCH,)CH—CH.CO.CH,;. The 
elucoside of this compound is obtained by the action of dilute 
caustic soda solution on glucovanillin and acetone, and crystal- 
lizes from boiling water in hght yellow needles, which contain 
two molecules of water and melt at 207°. The free methyl- 
feruloketone, which is prepared from this by means of emulsin, 
crystallizes in light yellow needles, which melt at 130° and 
dissolve readily in alcohol but only slightly in water. 


KETONIC ACIDS, C,,H,0,. 


2468 Cinnamylformic acid, C,H,.CH—CH.CO.CO,H. was first 
obtained from its nitril, but is more readily prepared by the 
action of hydrochloric acid on a mixture of benzaldehyde and 
pyroracemic acid :* 


C,H,.CHO + CH,.CO.CO,H = C,H,.CH—CH.CO.CO,H + H,0. 


It forms a syrup which dries to a gummy mass and is readily 
decomposed by aikalis into pyroracemic acid and benzaldehyde, 

Cinnamylformonitril, CgH;.CH—CH.CO.CN, is obtained by 
heating cinnamyl chloride with silver cyanide, and crystallizes 
from ether in prisms or tablets, melts at 114°—115° and is con- 
verted by the addition of concentrated hydrochloric acid to its 
solution in acetic acid into cinnamylformamide, C,H,.C,H,.CO. 
CO.NH,, which crystallizes from hot water in small plates or 
prisms, melting at 129°—130°4 

Benzoylacrylic acid, C,H,.;CO.CH—CH.CO,H, is formed by 
the action of aluminium chloride on a mixture of benzene and 
maleic anhydride, and crystallizes from hot water in lustrous 
satiny plates, which contain water, while it separates from 
toluene in needles, melting at 99°. On heating with alkalis it 
is resolved into acetophenone and glyoxylic acid, which is then 


1 Tiemann and Kees, Ber. Deutsch. Chem. Ges. xviii. 1955, 
2 Tiemann, 7zbid. xviii. 8492. 

3 Claisen and Claparede, ¢bid. xiv. 2472. 

4 Claisen and Antweiler, 2bid. xiii. 2123, 


338 AROMATIC COMPOUNDS. 


further converted into glycolic and oxalic acids. It yields 
benzoylpropionic acid and other products on _ reduction. 
When it is heated with acetic anhydride to 150°—160° in a 
sealed tube, lustrous, ruby-red needles or plates of a compound 
C,,H,O, separate out, which sublime on heating and dissolve in 
a mixture of benzene and petroleum spirit to form a rose-red 
solution with a golden-yellow fluoresence. It slowly dissolves in 
sulphuric acid to form a bright blue solution and is repre- 
cipitated by the addition of water. If the solution be heated, 
the colour changes to red, and a deep green fluorescence is then 
produced by the addition of water. Reducing agents convert 
the red compound, which is probably a quinone, into a colourless, 
crystalline substance. 


DIBASIC ACIDS, C,,H,0,. 


2469 Benzalmalonic acid, C,H;.C,H(CO,H),, is formed when 
a mixture of equal parts of benzaldehyde and malonic acid is 
heated with half its weight of glacial acetic acid for some hours 
on the water-bath; the following reaction taking place :? 


C,H,.CHO + CH,(CO,H), = C,H,.CH(OH)CH(CO,H), 
= C,H,.CH—C(CO,H), + H,0. 


It crystallizes from hot water in thick, vitreous prisms, which 
decompose on heating into carbon dioxide and cinnamic acid. 
The latter is also formed when the acid is boiled with water, but 
the chief products of this decomposition are benzaldehyde and 
malonic acid. It is converted into benzylmalonic acid by sodium 
amalgam and water. 

Hihyl benzalmalonate, C,H,.C,H(CO,.C,H,),, is readily ob- 
tained by passing hydrochloric acid into a mixture of ethyl 
malonate and benzaldehyde, and is a thick, almost odourless 
liquid, which boils at 196°—200° at a pressure of 13—14 mm. 
Small quantities can be rapidly distilled at the ordinary pressure, 
the boiling-point being 308°—312°. 

The three nitrobenzalmalonic acids have been prepared from 
the corresponding nitrobenzaldehydes.? 

1 Pechmann, Ber. Deutsch. Chem. Ges. xv. 881. 


* Claisen and Crismer, Ann. Chem. Pharm. ecxvili. 129. 
3 Stuart, Journ. Chem. Soc. 1888, i. 408 ; 1885, i. 155 ; 1886, i. 357. 


ETHYLPHENYLACETYLENE. 339 





Coumarincarboxylie acid, C,,H,O,, is the lactone of the un- 
known hydroxybenzalmalonic acid, and is formed by heating 
salicylaldehyde with malonic acid and glacial acetic acid 
to 100°: 


OH COOH onelvore: 
CHK + | = OFLC | + 2H,0. 
CHO CH,.CO.0H CH—C.CO.OH 


It crystallizes from hot water in white needles, which melt at 
187° and decompose into coumarin and carbon dioxide when 
more strongly heated.? 


HYDROCARBONS OF THE FORMULA, (,H,.0,H;. 


2470 Lthylphenylacetylene, C,H;.C=C.C,H,, is formed when 
a mixture of sodium phenylacetylene, ethyl iodide and ether is 
heated to 140° It is a strongly refractive liquid, which has a 
characteristic odour, boils at 201°—203° and has a sp. gr. of 
0923 at 21°. It combines at 150° with fuming hydrobromic 
acid to form ethylphenylvinyl bromide, C,H,.C,HBr.C,H,, a 
liquid, which smells like peppermint, decomposes on distilla- 
tion and is converted into ethylphenylvinyl acetate, C,H,.C,H 
(OC,H,0)C,H,, by heating with silver acetate and glacial acetic 
acid. 

This substance has a pleasant odour, boils at 223°—230° 
and on saponification yields ethylphenylvinyl alcohol, CgH,.C,H 
(OH)C,H,, which is also a pleasant-smelling liquid and boils 
at 224°—226°. Its constitution is represented by one of the 
following formule :? 


C,H,.CH—C(OH)C,H, C,H,.C(OH)—CH.C,H,. 


Phenylerotonylene, C,H;.CH,.C=C.CH,, was obtained by 
Aronheim by heating phenyl-8-butylene dibromide (p. 326) 
with alcoholic potash. It is a liquid, which boils at 185°—190° 
and does not give a silver compound. 


1 Stuart, Journ. Chem. Soc. 1886, i. 365. 
2 Morgan, zbid. 1876, 1. 162. 


340 AROMATIC COMPOUNDS. 


INDOLS, C,,H,,N. 


2471 The following have been investigated :* for explanation 
of the nomenclature see page 269 : 
Veal 
Pr2-3-Dimethylindol, C,H, SsC—CH,. 
\ni 


Roel 

Pr1®-2-3-Trimethylindol, Colla Ss C—CHs. 
N-—CH, 

Uy Seaees 

B3Pr-2-Dimethylindol, EE EES pela 
NL 
Paces 

Pr3-Ethylindol, C,H, SSCH. 

\wit 

Pr2-3-Dimethylindol is formed when methylindolacetic acid, 
which is the corresponding carboxylic acid, is heated and when 
the phenylhydrazone of methylethylketone is heated to 180° 
with zinc chloride. It crystallizes in small plates, smells like 
indol, melts at 106°, boils at 285° and does not colour a pine- 
splinter which has been moistened with hydrochloric acid. Its 
picrate forms red needles. 

Trimethylindol is obtained by heating dimethylindolacetic acid 
and is an oily liquid, which boils at about 280°, has only a faint 
odour, does not colour pine-wood and also forms a picrate, which 
crystallizes in dark red needles. 

L3-Pr2-Dimethylindol is prepared in a similar manner to 
methylketol from acetoneparatolylhydrazone ; it forms crystals, 
which melt at 114°—115° and yields a picrate crystallizing in 
dark red needles and melting at 155°. 

Pr3-Hthylindol is obtained by heating lactic acid with aniline 
and zine chloride. It is a light yellow liquid, which has a 
feecal odour, boils at 282°—284° and gives the pyrrol reaction. 
The addition of bromine to its solution in chloroform pro- 
duces a deeply-coloured solution resembling one of potassium 
permanganate. Its picrate is readily soluble in benzene and 
is precipitated from this solution in red flakes, which melt 
at 143°. 

1 Fischer, Ann. Chem. Pharm. ccxxxvi. 216 ; Degen, ibid. cexxxvi. 151 ; 


Raschen, ibid. ccxxxix. 223. 
2 Pictet and Dupare, Ber. Deutsch. Chem. Ges. xx. 3415. 


SKATOLCARBOXYLIC ACID. 341 


INDOLCARBOXYLIC ACIDS CONTAINING TEN 
CARBON ATOMS. 


The following members of this group are known: 


—CH, 


sain 
Skatolcarboxylic acid, C,H, C—co, H. 


‘\ WH 


yee. H 
Pr1”-2-3-Dimethylindolcarboxylic acid, OH ANG ae 


ae tea tee. H 
‘\ Co 
CH,.C,H 


Indoldicarboxylic acid, C,H,— 


B3-Pr2-Methylindolearboxylic acid ) 


H 
B1-Pr2-Methylindolcarboxylic acid § >C—-CO,H 


<NH 

Skatolcarboxylic acid is an invariable product of the putrefac- 
tion of egg-atbumen?+ and appears to be a normal constituent of 
human urine.” It crystallizes from benzene in odourless plates, 
which melt at 164° and decompose at a higher temperature into 
skatol and carbon dioxide. The dilute, 0:1 per cent. solution is 
coloured cherry-red by the addition of a few drops of pure nitric 
acid followed by a small quantity of potassium nitrite solution, 
and a red colouring-matter separates out on standing, while a 
purple-red colouring-matter is produced when the solution is 
mixed with an equal volume of hydrochloric acid of sp. gr. 1:2 
and heated with a few drops of bleaching powder solution. 
When ferric chloride is added to a solution of skatolcarboxylic 
acid made faintly acid with hydrochloric acid, an intense violet 
colouration is produced even in a solution containing only 0°001 
per cent. 

Pr12-2-3-Dimethylindolearboxylic acid, The ethyl ether of this 
acid is obtained by heating the methylphenylhydrazone of aceto- 
acetic ether with zinc chloride and yields the free acid on treatment 
with alcoholic potash and decomposition of the product with 
dilute sulphuric acid. It crystallizes from hot alcohol in small, 
lustrous, six-sided tablets, which melt at 185° with partial 
decomposition and decompose at 200°—205° into carbon dioxide 
and dimethylindol (p. 269).* 


1 H. and E. Salkowski, Ber. Dewtsch. Chem. Ges. xiii, 191; xviii. Ref. 410. 
2 [bid. xviii. Ref. 411. 
3 Degen, Ann. Chem. Pharm. cexxxvi. 157. 


342 AROMATIC COMPOUNDS. 


Indoldicarboxylic acid. When metahydrazinebenzoic acid is 
treated with pyroracemic acid in faintly acid solution, the cor- 
responding hydrazone, C,,H,)N,O,, 1s formed and is converted 
into the ethyl ether by heating with sulphuric acid and alcohol. 
This ether, on heating to 215°—220° with zine chloride, yields 
among other products the mono-ethyl ether of indoldicarboxylic 
acid, from which the free acid may readily be prepared. It 
crystallizes from hot alcohol in fine needles, melts with evolu- 
tion of gas at 250°, carbonization taking place and a small 
quantity of distillate being obtained, which appears to contain 
indol,} 

B3-Pr2-Methylindolearboxylic acid has been prepared from 
pyroracemic acid paratolylhydrazone and crystallizes from hot 
water in needles, which melt at 227°— 228° and decompose into 
carbon dioxide and B3-methylindol at 235°—240°. 

Bi -Pr2-Methylindolcarboxylic acid forms needles, which melt 
at 170°—171° and only yield a very small amount of Bl-methy]- 
indol when more strongly heated (Raschen). 


1 Roder, Ann. Chem. Pharm. ccexxxvi. 167. 


THE LAURENE GROUP. 343 


THE LAURENE GROUP. 
THE HYDROCARBONS OF THE FORMULA, C,H, 


2472 The first member of this group to be synthetically pre- 
pared was amylbenzene, which was obtained by Fittig and 
Tollens. The isomeric laurene, after which the group is named, 
was then obtained, accompanied by other products, by the 
distillation of camphor with zinc chloride (Fittig, Kobrich, and 


Jilke). 


PENTAMETHYLBENZENE, C,H(CH,),. 


This body was discovered by Friedel and Crafts, who obtained 
it, together with other methylated benzenes, by the action of 
methyl chloride on benzene and toluene in presence of alum- 
inium chloride. As already mentioned, the latter yields 
orthoxylene, together with a little paraxylene and _ still less 
metaxylene. On further methylation, the dimethylbenzenes 
are converted into pseudocumene, metaxylene yielding some 
mesitylene in addition. The former of these then passes into 
durene and the latter into isodurene, both of which finally 
yield pentamethylbenzene and hexmethylbenzene, which can 
therefore be readily obtained directly from mesitylene.? The 
methylation of benzene can therefore be expressed by the follow- 
ing diagram, the chief products being italicised (Jacobsen). 

Orthoxylene Me 
Toluene—Paraxylene —Pseudocumene - Dur oh, 


Metaxylene Penta- and 


Mesitylene - [esdurenbes 
Hexmethylbenzene. 


1 Ann. Chim. Phys. [6] i, 459 ; Ador and Rilliet, Ber. Deutsch. Chem. Ges. xii. 
9, 2 Jacobsen, ibid. xiv. 2624 ; xx. 896. 


288 


344 AROMATIC COMPOUNDS. 


Pentamethylbenzene crystallizes in large plates, melts at 53° 
and boils at 229°. 

Bromopentamethylbenzene, CBr (CHs)s5 4 is formed by a action 
of bromine on the hydeeeeoen in chloroform solution ; the re- 
action is assisted by the presence of a trace of iodine. ‘Tt forms 
white crystals, melts at 163° and boils at 292". 

Pentamethylsulphonie acid, C,(80,H)(CH,),, is not formed 
when the hydrocarbon is agitated with sulphuric acid, the pro- 
ducts in this case being hexmethylbenzene and _prehnitene- 
sulphonic acid (p.277). It may however be obtained by gradually 
bringing the hydrocarbon into well-cooled chlorosulphonic acid, 
the sulphone being also formed. The sodium salt, C,(SO,Na) 
(CH,),, crystallizes in tabular crusts and is only slightly soluble 
in hot water. Ifit be agitated with sulphuric acid in presence 
of petroleum-spirit until complete solution has taken place, the 
latter leaves a residue of pure pentamethylbenzene on evapora- 
tion (compare p. 275). 

Pentamethylbenzenesulphonie chloride, C,(SO,Cl)(CH,);, erys- 
tallizes from warm alcohol in small plates and from ether in 
large flat prisms, melting at 82". 

Pentamethylbenzenesulphonamide, C,(SO,.N H,)(CH,);, separates 
from hot alcohol in large, flat, lustrous prisms, which melt at 186° 

Pentamethylphenol, C,(OH)(CH,);, was obtained by Hofmann 
by suspending the sulphate of amidopentamethylbenzene in a 
solution of potassium nitrite and adding dilute sulphuric acid 
to the well-cooled: mixture until complete solution had taken 
place. It crystallizes from alcohol in fine needles, has the 
characteristic smell of phenol, melts at 125°, boils at 267° and 
is volatile with steam. Ferric chloride produces no colouration 
and caustic soda only dissolves it on warming. 

Pentamethylphenyl methyl ether, C, .(OCH,)(CH), crystallizes 
from alcohol in long needles, melting at 63°—64. 

Amidopentamethylbenzene, C,(NH,)(CH, is formed when 
dimethyl-a-pseudocumidine is heated with methyl iodide to 
24.0°—250°. It crystallizes from dilute alcohol in large white 
needles, melts at 151°—152° and boils at 277°—278°. 


Melting-point. 
Methylamidopentamethylbenzene, C,(CH,),.NH(CH,). 60°—61° 
Dimethylamidopentamethylbenzene, C,(CH;),N(CH,),. 53°—54° 
Acetamidopentamethylbenzene, C,(CH;);NH(C,H,O) . 213° 


1 Jacobsen, Ber. Deutsch. Chem. Gries. xx. 896. 


THE LAURENE GROUP. 345 


These compounds crystallize in needles; the dimethylated 
base does not combine with methyl iodide even at 170°. 

Pentamethylphenylearbamine, C,(NC)(CH,);, has been pre- 
pared by heating the amido-base with alcoholic caustic soda 
and chloroform, and forms colourless crystals, melting at 
127°—128°, which, although exceedingly unpleasant, do not 
possess such an overpowering odour as the more volatile 
carbamines. When heated above its melting point, it changes 
with evolution of heat into the isomeric nitril, C,(CN)(CH,),, 
which crystallizes from alcohol in white needles, melting at 
168° and boils at 290°—292°. It has been found Pi Nesaible 
to convert this substance into the corresponding amide or acid. 
It is not attacked by sulphuric acid at 100° or hydrochloric acid 
at 180°, while at 250° it is partially carbonized. On heating to 
220°—230° with concentrated hydriodic acid, it is decomposed 
into ammonia, carbon dioxide and pentamethylbenzene, so that 
in this respect it resembles the corresponding derivates of 
isoduridine (p. 276). 

Pentamethylphenylthiocarbimide, C,(NCS)(CH,);, is formed, 
together with the corresponding thiocarbamide by the continued 
heating of the amido-base with carbon disulphide. The mustard 
oil passes over on distillation with steam. It crystallizes from 
alcohol in needles, melting at 86°. 

Tetramethylbenzenccar bee ylic acid, C,H(CH,),CO,H, is formed 
by the oxidation of pentamethylbenzene with dilute nitric acid 
and crystallizes from alcohol in fascicular groups of needles, which 
melt at 165°. On heating with caustic lime it yields prehnitene, 
its constitution being thus ascertained.? 

Trimethylbenzenedicarborylic acid, C,H(CH,),(CO,H),, has 
been obtained by the oxidation of durylphenylketone, C,H(CH,), 
CO.C,H,, with potassium permanganate and crystallizes from 
water in needles, which melt at 210°. On heating the solution 
of the ammonium salt with barium chloride, the compound 
C,H(CH,),(CO,),.Ba + H,O is precipitated in fine needles.* 

Benzenepentacarboxylre acid, C,H(CO,H); + 6H,O, is formed 
when finely powdered pentamethylbenzene is added to a solution 
of potassium permanganate and the mixture allowed to stand for 
a month. It is left on the evaporation of its solution as an 
amorphous mass, which loses its water on heating, then melts 


1 Hofmann, Ber Deutsch. Chem. Ges. xviii. 1821. 
2 Gottschalk, zbid. xx. 3286. 
3 Ador and Meyer, Jahresber. Chem. 1879, 562. 


346 AROMATIC COMPOUNDS. 








and finally yields a crystalline sublimate, a portion being simul- 
taneously carbonized. It forms a characteristic calcium salt, 
(C,,HO,,),.Ca, which crystallizes very slowly in spherical aggre- 
gates of small needles. The salts of most of the metals produce 
amorphous precipitates in a solution of the acid neutralized with . 
sodium carbonate (Friedel and Crafts). 


S-METHYLDIETHYLBENZENE, (,H,(CH,)(C,H,)». 


2473 This substance was prepared by Jacobsen, together 
with mesitylene, dimethylethylbenzene and a small quantity 
of triethylbenzene, by distilling a mixture of acetone and 
methylethylketone with sulphuric acid. It is also a constituent 
of Caucasian petroleum?! and is a liquid boiling at 198°—200°, 
which has a specific gravity of 0°879 at 20°. On oxidation with 
nitric acid it yields uvitic acid. 

Tribromomethyldiethylbenzene, C,Br,(CH,)(C,H,),, crystallizes 
from hot alcohol in fine needles, melting at 206°? 

Dethylbenzore acid, C,H,(C,H,;),CO,H, is formed, together 
with hydrogen and benzoic acid, when diethylcarbobenzonic acid, 
C,,H,,O,, 18 heated with caustic potash and is an oily liquid; 
the silver salt crystallizes in small plates. 


THE DIMETHYLPROPYLBENZENES, 
CgH;(CH,).0,H;. 


2474 s-Dimethylpropylbenzene has been prepared by Jacobsen 
from acetone and methylpropylketone ; it boils at 210° and is 
oxidized by nitric acid to mesitylenic acid. 

Laurene is formed, together with lower homologues, by the 
distillation of camphor with zinc chloride and boils at 188°. 

Tribromolawrene, C,Br,(CH,) C,H, crystallizes from alcohol in 
long needles, melting at 125°.° It was supposed by Montgolfier 
that laurene was isomeric with cymene © whilst Armstrong and 
Muller considered it to be identical with ethylorthoxylene.’ Reuter 

1 Markownikow, Ann. Chem. Pharm. ccxxxiv. 107. 

2 ber. Deutsch. Chem. Ges. vii. 1430. 

3 Ann. Chem. Pharm. elxxxiv. 172. 

4 Ber. Deutsch. Chem. Ges. viii. 1259. 

> Fittig, Kobrich, and Jilke, Ann. Chem. Pharm. exlv. 129. 


6 Ann. Chim. Phys. [5] xiv. 91. 
7 Ber. Deutsch. Chem. Ges. xvi. 2258. 


DIMETHYLPROPYLBENZENE. 347 


has however found that it is a mixture of two dimethylpropyl- 
benzenes, which can readily be separated by means of their 
sulphonic acids.? 

a-Laurene (C,H, : CH, : CH,=1 : 3: 4) boils at 190°—191°, 
is oxidized to paraxylic acid by nitric acid and yields bromine 
derivatives, which all crystallize well. 

a-Laurenesulphonie acid, C,H,(C,H,)(CH,),SO,H, forms well- 
developed, asymmetric crystals. 

Sodium laurenesulphonate, C,,H,,SO,Na, crystallizes in large, 
transparent plates. 

Barium laurenesulphonate, (C,,H,;5O,),Ba+5H,0, forms 
long, six-cornered crystals. 

a-Laurenesulphonamide, C,,H,,5O0,.NH,, crystallizes in long 
needles, which melt at 127°. 

B-Laurene (1: 2:4) boils at 184°—186°, and is oxidized to 
xylic acid by nitric acid. Its sulphonic acid is liquid and forms 
amorphous, readily soluble salts ; the sulphonamide only becomes 
solid after standing for weeks. 

Methylpropylbenzoic acid or Cymenecarboxylie acid, C,H3(C.H,) 
(CH,)CO,H(1 :4:3). The nitril is obtained by the distillation 
of sodium cymenesulphonate with potassium cyanide and is 
converted by heating with alcoholic potash into the amide, from 
which the acid may be obtained by heating with hydrochloric 
acid. The free acid crystallizes in fine needles, melting at 63°. 

Propylorthotoluie acid (1: 4:2). The nitril of this acid is 
formed when carvacryl phosphate, [C,H,(CH,)C,H,],PO,, is 
heated with potassium cyanide. It is an aromatic smelling 
liquid, which boils at 244°—246°. The corresponding acid 
crystallizes from dilute alcohol in needles, melting at 75°.% 

Thymotic acid, O,H,(OH)C,H,(CH,)CO,H(2: 1:4: 3), is 
obtained by passing carbon dioxide into a mixture of thymol 
and sodium ; it forms small, silky crystals, which are only slightly 
soluble even in hot water, melt at 123° (Kobek) and volatilize 
with steam. It gives a deep blue colouration with ferric chloride.‘ 

Thymotide, C,,H,,0,, corresponds to salicylide (Pt. IV. p. 308) 
and is formed when the acid is heated with phosphorus pent- 
oxide or the potassium salt with phosphorus pentachloride ; it 
crystallizes in needles and melts at 187°.° 


1 Reuter, Ber. Deutsch. Chem. Ges. xvi. 624. 

2 Paterno and Fileti, Gaz. Chim. Ital. v. 30. 

3 Kreysler, Ber. Deutsch. Chem. Ges. xviii. 1714. 

4 Kolbe and Lautemann, Ann. Chem. Pharm. exv. 205, 
5 Naquet, Bull. Soc. Chim. iv. 92. 


348 AROMATIC COMPOUNDS. 


Parathymotie acid (2:1:4:5). The aldehyde of this acid 
is obtained by heating thymol with caustic soda and chloroform, 
and crystallizes from hot water, in which it is only very slightly 
soluble, in long, silky needles, which melt at 133°. The acid 
may be obtained in a similar manner by employing tetrachloro- 
methane instead of chloroform in the reaction. It crystallizes 
from dilute alcohol in broad, white plates, melts at 157° and 
gives no reaction with ferric chloride.? 

Carvacrotie acid (3: 1:4:2) has been prepared by treating 
carvacrol with sodium and carbon dioxide, and crystallizes from 
hot water in long, smooth needles, which melt at 131° (Lustig) 
and readily sublime. It gives a bluish-violet colouration with 
ferric chloride.” 

Paracarvacrotie acid (8: 1:4:6). The aldehyde of this acid 
is formed when carvacrol is heated with chloroform and caustic 
soda, and is a heavy, oily quid, which decomposes on distillation, 
but is volatile with steam. It is readily oxidized by exposure 
to the air, more rapidly by a cold solution of potassium 
permanganate. 

Paracarvacrotic acid crystallizes from hot water in very fine 
silky needles, which melt at 80°, readily sublime and give a 
green colouration with ferric chloride.? 

Cymenotie acid (4: 1:3: 5), has been prepared by the action 
of sodium and carbon dioxide on meta-isocymophenol (p. 302). 
It is only slightly soluble in hot water, from which it crystallizes 
in long, fine needles, melting at 147°. It gives a bluish violet 
colouration with ferric chloride.‘ 


METHYLBUTYLBENZENES OR BUTYL- 
TOLUENES. 


2475 Meta-isobutyltoluenc, C,H,(CH;)CH,.CH(CH;)., was dis- 
covered by Kelbe in spirit of resin,®> and synthetically prepared 
by the action of isobutylbromide on a mixture of toluene and 
aluminium chloride. The butyltoluene, which Goldschmidt 


1 Kobek, Ber. Deutsch. Chem. Ges. xvi. 2096. 

2 Kekulé and Fleischer, bid. vi. 1087. 

3 Lustig, dbid. xix. 11. 

4 Jesurun, 2bid. xix. 1418. 

5 Kelbe, zbid. xiv. 1240; Renard, Ann. Chim. Phys. [6] i. 250. 
° Kelbe and Baur, zbid. xvi. 2559. 


THE METHYLBUTYLBENZENES. 349 


obtained by heating isobutyl alcohol with toluene and zinc 
chloride to 300°, is probably identical with this substance.? 

It is extracted from resin spirit by converting the fraction 
which boils at 190°—200° into the sulphonic acids and preparing 
the pure lead salt, which is then decomposed by heating with 
hydrochloric acid. It is a strongly refractive liquid, which has a 
pleasant odour, boils at 186°—188° and is oxidized by chromic 
acid to isophthalic acid. 

| Meta-isobutyltoluenesulphamide, C,H;(SO,.N H,)(C H,) C,H, 
crystallizes from water in small, lustrous plates, which melt 
at 74°—75°. 

Isobutylorthocresol, C,H,(0H)(CH;)C,H,, has been obtained 
from the following compound: by means of the diazo-reaction, as 
a thick liquid, which has a faint aromatic odour and boils at 
235°—237°. 

a-Isobutylorthotoluidine, C,H,0NH,)CH,.C,H,(6:1:3), is 
prepared by heating orthotoluidine hydrochloride with isobutyl 
alcohol to 200°—300°, and is a pleasantly aromatic smelling 
liquid, which boils at 243° and yields a diazo-salt, which is 
converted into meta-isobutyltoluene by heating with stannous 
chloride.” 

v-Isobutylorthotoluidine (2:1:3), is formed when  ortho- 
toluidine is heated to 280° with isobutyl alcohol and zinc 
chloride,? and is a liquid which has a less pleasant odour than 
the preceding compound, boils at the same temperature and 
may also be converted into meta-isobutyltoluene by the diazo- 
reaction. 

These bases can easily be separated by means of their salts and 
other derivatives. Their constitution follows from the facts that 
the first described forms a mustard oil, which on heating with 
copper yields the nitril of isobutylorthotoluic acid, C,H,(CH,) 
(C,H,)CO,H, the free acid corresponding to which is converted 
by oxidation into trimellitic acid, and that only two isomeric 
amido-bases can be formed by the reaction employed in their 
preparation. 

Para-isobutyltoluene also occurs in essence of resin and is 
formed, together with the meta-compound, by the aluminium 
bromide synthesis.* It is a liquid, which has a pleasant smell 
and boils at 176°—178". 


1 Ber. Deutsch. Chem. Ges. xv. 1066. 

2 Effront, ibid. xvii. 2317. 

3 Erhardt, dbid. xvii. 419; Effront, loc. cié. 
4 Kelbe and Pfeiffer, cbid. xix, 1723. 


350 AROMATIC COMPOUNDS. 


Para-isobutylioluencsulphamide crystallizes in large, vitreous 
plates, which melt at 113°. 

Meta-isobutylbenzoie acid, (CH,),C,H,.C,H,.CO,H, is formed 
by the oxidation of meta-isobutyltoluene with dilute nitric acid, 
the reaction being somewhat exceptional inasmuch as the more 
complex side chain is not attacked. It crystallizes in long broad 
needles, melting at 127°; on heating to 170°—200° with nitric 
acid, isophthalic acid is formed (Kelbe and Pfeiffer). 

Para-isobutylbenzotc acid, which is formed in a similar manner 
from para-isobutyltoluene, was first synthetically prepared by 
Pahl, who converted isobutylphenyl mustard oil ito para- 
isobutylbenzomitril, C,H).C,H,CN, by heating it with copper 
dust. The nitril is an aromatic smelling liquid, which boils at 
248° and is converted into the acid by heating with alcoholic 
potash.1 The free acid is also formed when isobutylformanilide, 
C,H,.C,H,N(COH)H, is heated with zinc dust,? and when 
isobutylphenyl phosphate is heated with potassium cyanide.® 
Para-isobutylbenzoic acid forms needles or monosymmetric 
crystals, which resemble those of calc spar in shape and melt 
at 164°. It is oxidized to terephthalic acid by potassium per- 
manganate or by nitric acid at 170°—200°. 

Both these acids are resolved into carbon dioxide and isobutyl- 
benzene by heating with lime. 

Para-isobutylorthohydroxybenzenecarboxylic acid, (CH,),C,Hs. 
C,H;(OH)CO,H, is homologous with salicylic acid and is formed 
in a similar manner when the sodium compound of isobutyl- 
phenol is heated with carbon dioxide. It is scarcely soluble in 
cold, only shghtly in hot water, from which it crystallizes in very 
fine, long, white lustrous needles, which are decomposed again 
into isobutylphenol and carbon dioxide by heating to 180°—190° 
with hydrochloric acid. Its aqueous solution is coloured deep 
violet by ferric chloride. The methyl ether crystallizes from 
wood-spirit in splendid, monosymmetric prisms, melts at 54° 
and boils at 266°.4 

Parapropylphenylacetic acid or Homocuminie acid, C,H,(C,H,) 
CH,.CO,H, is a derivative of the still unknown propylethyl- 
benzene. Its nitril is formed when cymyl chloride is heated 
with potassium cyanide and alcohol, and yields the acid on 


1 Ber. Deutsch. Chem. Gtes. xvii. 1236. 

Gasiorowski and Merz, zbid. xviii. 1009. 

Kreysler, 7b¢d. xviii. 1706. 

v. Dobrzycki, Journ. Prakt. Chem. [2] xxxvi. 389. 


- w bo 


THE PENTYLBENZENES. 351 





boiling with caustic potash. This crystallizes from hot water in 
small needles, melting at 52°1 On distillation with caustic 
lime, ordinary cymene is formed.” 


THE PENTYLBENZENES. 


2476 Pentylbenzene, C,H;.C;H,,, has been obtained by 
Schramm by the action of sodium on a mixture of benzyl 
bromide and butyl bromide. It is a very pleasant smelling 
liquid, which boils at 200°5°—201:5° and has a sp. gr. of 
0'8602 at 22°.3 

Phenylpentoxylic acid, C,H;.C,H..CO,H, is formed when 
cmnamenylacrylic acid,C,H,.CH—CH.CH—CH.CO,H, is heated 
to 160° with a saturated solution of hydriodic acid in glacial 
acetic acid. It is readily soluble in the usual solvents, with the 
exception of water, from which it crystallizes on cooling in plates, 
which melt at 58°—59°.4 


O 
Piperhydronie acid, CH Droh:me ,H,.CO,H, is obtained by 
O 


the long-continued heating of 8-hydropiperic acid with sodium 
amalgam and water, the liquid being kept neutral by the 
addition of hydrochloric acid. It may also be prepared, and 
apparently more readily, from $-bromohydropiperic acid, It 
crystallizes from dilute alcohol in small, thin tablets, which melt 
at 96°5 

Amylbenzene, C,H;.C,H,.CH(CH,),, was prepared by Fittig 
and Tollens, who treated a solution of amyl bromide and bromo- 
benzene in benzene with sodium.® <A. better yield is obtained 
when ether is used as a diluent instead of benzene (Schramm). 
It is also formed by the action of amyl chloride on a mixture 
of benzene and aluminium chloride’ and is a pleasant smelling 
liquid, which boils at 193° and has a sp. gr. of 0°859 at 12°. 

Tribromamylbenzene, C,H,Br..C,H,,, crystallizes in needles, 
which melt at 140° and are readily soluble in hot alcohol (Bigot 
and Fittig). 

1 Rossi, Ann. Chem. Pharm. Suppl. i. 139. 

2 Paternd, Ber. Deutsch. Chem. Ges. xvii. Ref. 109. 

3 Schramm, Ann. Chem. Pharm. ecxviii. 383. 

4 Baeyer and Jackson, Ber. Deutsch. Chem. Ges. xiii. 122. 

5 Fittigand Buri, Ann. Chem. Pharm. cexvi. 176. 


6 Ann. Chem. Pharm. cxxix. 369 ; cxxxi. 313 ; Bigot and Fittig, zbid. exli. 160. 
7 Friedel and Crafts, Ann. Chim. Phys. [6] i. 454. 


352 AROMATIC COMPOUNDS. 


Amylphenol, C,H,(OH)C;H,,, is formed when phenol, amyl 
alcohol and zinc chloride are heated together to 180°) and 
crystallizes from hot water, in which it is only slightly soluble, 
in long needles, melting at 92°—93°. It boils at 255° and yields 
amylphenyl methyl ether, C,H,(OCH;)C,H,,, on heating with 
wood spirit, methyl iodide and caustic potash. This ether is a | 
liquid, which boils at 216°—217° and is oxidized to anisic acid 
by chromic acid.? 

Amylamidobenzene, C,H,(NH,)C,H,,, was obtained by Hofmann 
by heating amylaniline hydrochloride to 300°—840°3 It is also 
formed when amy] alcohol is heated to 270° with anilin and zine 
chloride,‘ and is a liquid, which boils at 256°—258° and is con- 
verted by the diazo-reaction into amylphenol. 

o-Diethyltoluene or Diethylphenylmethane, C,H;.CH(C,H,),, is 
formed by the action of zinc ethyl on benzidene dichloride,° 
C,H,;.CHCl,, and benzenyl trichloride, C,H,.CCl,, ethylene 
being simultaneously formed in each case.6 It has also been 
prepared by heating diethylhomophthalic acid, C,H,.C(C,H,), 
(CO,H), with soda lime.’ It is a liquid, which boils at 
178°. 

a-Lihyl-B-phenylpropionie acid or Benzylbutyric acid,C,H;.CH,,. 
CH(C,H,)CO,H, is an oily liquid, which boils at 272° and is 
formed by the action of sodium amalgam and water on 
phenylangelic acid§ 

Benzyl benzylbutyrate, C,H;.CH,.CH(C,H,)CO,.CH,.C,H,, is 
formed by the action of sodium on benzyl butyrate (Pt. IV. 
p. 98) and is a liquid, which boils at 330°—340°. 

Benzyl benzylisobutyrate, C,H;.CH,.C(CH,),.CO,.CH,.C,H,, 
has been prepared in a similar manner from benzyl isobutyrate ; 
it boils at 285° and is resolved into toluene, isobutyric acid and 
benzoic acid on heating with soda lime to 200°.1° 

Lihylhydrocarbostyriul, C,,H,,NO. Benzylbutyric acid yields 
an oily nitro-product, which is converted by reduction into 
ethylhydrocarbostyril (p. 169). This substance forms small 


1 Liebmann, Ber. Deutsch. Chem. Ges. xiv. 1842 ; xv. 150. 
2 Kreysler, dbid. xviii. 1706. 

8 Ibid. vii. 526. 

4 Merz and Weith, zbid. xiv. 2342 ; Calm, zbid. xv. 1462. 

> Lippmann and Luginin, Zeitschr. Chem. 1867, 674. 

6 Dafert, Monatsh. Chem. iv. 153. 

7 Pulvermacher, Ber. Deutsch. Chem. Ges. xx. 2495. 

8 Baeyer and Jackson, ibid. xiii. 115. 

® Conrad and Hodgkinson, Ann. Chem. Pharm. exciii. 318. 
10 Hodgkinson, Ann. Chem. Pharm. cci. 166. 


BUTENYLMETHYLBENZENE. 353 


crystals, melting at 87°—88° and has the following constitution 

(Baeyer and Jackson) : 

/ oH CH.CH, 

CoH 
NH—CO 


Dimethylethylphenylmethane, C,H;.C(C,H;)(CH3)., 1s formed 
by the action of aluminium chloride on a mixture of benzene 
and tertiary amylchloride or trimethylethylene, and is a liquid, 
which boils at 185°—190°.? 


HYDROCARBONS, ©,,H,,, AND THEIR 


DERIVATIVES. 


2477 Butenylmethylbenzene, CH,.C,H,.CH,.CH,.CH=CH,, 
which is also called tolylbutylene, is obtained, together with 
diallyl and dixylyl, by the action of sodium on a mixture of 
allyl iodide and metaxylyl chloride. It is an aromatic smelling 
liquid, which boils at 195° and forms a liquid dibromide.* 

Para-isopropylstyrolene, (CH,),CH.C,H,.CH—CH,, is formed 
when cumenylacrylic acid, (CH,),CH.C,H,.C,H,.CO,H, is heated, 
and by the action of sodium carbonate on bromohydrocumenyl- 
acrylic acid. It is an aromatic smelling liquid, which boils at 
203°—204°, a considerable amount of para-isopropylmetastyrolene 
being thus formed and left behind.® 

Para-iopropylstyrolene bromide, (CH,),CH.C,H,.CHBr.CH,Br, 
erystallizes from alcohol in lustrous needles melting at 71°. 

Para-isopropylmetastyrolene, (C,,H,,),, 1s formed, as stated 
above, by heating the hydrocarbon for some time to 150°, or 
when it is exposed to the light for one or two months. Like 
metastyrolene itself, it is a vitreous mass, which is reconverted 
into para-isopropylstyrolene by strongly heating. 

Pentenylbenzene or Phenylpentylene, C,H,.CH—CH.C,H.. 
When bromine vapour is allowed to act upon pentylbenzene at 
150°, the monobromide, C,H,.C,H,,Br, is obtained and decom- 
poses on distillation into hydrobromic acid and pentenylbenzene. 
It is a liquid, which boils at 210°—215. 


1 Essner, Bull. Soc. Chim. xxxvi. 212. 
2 Aronheim, Ber. Deutsch. Chem. Gres. ix. 1789. 
3 Perkin, Jowrn. Chem. Soc, 1877, i. 401 ; ii. 668. 


354 AROMATIC COMPOUNDS. 


Phenylpentenyl dibromide, C,H;.C;,H br, forms needles or 
small plates, which melt at 53°—54°.1 

Amenylbenzencor Phenylamylene,C,H,.C H—CH.CH(CH,),,was 
obtained by Schramm in a similar manner from amylbenzene, 
as a liquid, boiling at 200°5°—201°5°. 

Phenylamylene dibromide, C,H,.C;H,Br,, is formed when the 
olefine is combined with bromine and also when amylbenzene is 
treated with bromine vapour at 150°. It crystallizes from hot 
alcohol in silky needles, which melt at 128°—129°. 

Phenlyamylenglycol, C,H;.CH(OH)CH(OH)CH(CH,),, is 
obtained by treating a mixture of benzaldehyde and isobutyr- 
aldehyde with alcoholic potash or sodium amalgam and 
separates from benzene in crystals, which have an aromatic 
odour and melt at 81°—82°? 

Phenylethylpropylene,C,H,.CH(C,H,)CH—CH,. Whendiethyl- 
phenylmethane is treated at the boiling point with bromine, the 
compound C,H,.CH(C,H,)CHBr.CH,, is formed as an oily 
liquid, the vapour of which attacks the eyes very violently, and 
which is converted into the olefine by boiling with water or 
alcoholic potash. The latter is a strongly refractive, pleasant 
smelling liquid and boils at 173°, being partially converted into 
diphenylethylpropylene, C,,H,.. This body boils at 208°—212° 
and does not combine with bromine, so that it probably has the 
following constitution :° 


C,H,.(C,H,)CH.CH.CH, 


| 
C.H,.(C,H,)CH.CH.CH, 


HYDROXY-ACIDS, ©,,H,,03. 
2478 Phenylpropylglycolic acid, C,H,(C,H,)CH(OH)CO,H, is 


formed by the action of hydrocyanic acid and hydrochloric acid 
on cuminaldehyde.* In order to prepare it, the aldehyde is 
diluted with ether, the necessary amount of powdered potassium 
cyanide added and the calculated quantity of fuming hydro- 
chloric acid allowed to drop slowly into the well cooled mixture. 


1 Schramm, Ann. Chem. Pharm. ccxviil. 392. 
2 Fossek, Monatsh. Chem. v. 119. 

3 Dafert, ibid. iv. 616. 

4 Raab, Ber. Deutsch. Chem. Ges. viii. 1148. 


PHENYLPROPYLGLYCOLIC ACID. 355 


The nitril is left after the evaporation of the ether as an oily 
liquid, which is converted into the acid by the action of cold, 
fuming hydrochloric acid.t_ The free acid crystallizes from 
water in small, white needles, melting at 158°. 

Phenythydroxylpwalie acid, C,H,.CH(OQH)C(CH,),CO,H, is 
obtained by heating benzaldehyde with sodium isobutyrate and 
acetic anhydride or isobutyric anhydride and boiling the product, 
which consists of acetyl- or isobutyryl-phenylpivalic acid, with 
baryta water. It is only slightly soluble in cold, readily in hot 
water, from which it crystallizes in feathery groups of needles, 
which melt at 134° and decompose at 190° into carbon dioxide, 
water and butenylbenzene.” 

It was stated in the discussion of the formation of cinnamic 
acid, that phenyl-lactic acid is probably formed as an intermediate 
product but immediately loses water. This view is confirmed 
by the formation of phenylhydroxypivalic acid, which cannot 
pass into a homologue of cinnamic acid by loss of water. 
ak (OH)CH, 
Benzylhydroxybutyric acid, C,H,.CH,.CH, 
*\CO,H 
formed by the action of water and sodium amalgam on benzyl- 
acetoacetic ether (p. 358). It crystallizes on the evaporation of 
the alcoholic solution in thin prisms, whilst, when the hot aqueous 
solution is allowed to cool, the liquid becomes turbid and deposits 
a precipitate of hair ike needles, melting at 152°—155°.8 

Hydroxypiperhydrone acid, C,,H,,0;, may be readily obtained 
by decomposing dibromopiperhydronie acid with alkalis : 


, is 


on. ye, H,.CH,,CHBr.CHBr.CH,.CO,H + H,O = 


1 ° o,H, CH, C(OH)=CH.CH, C,H + 2HBr. 
O 


The hydroxy-acid thus formed passes immediately, as in 
analogous cases, into puperoketonic acid, CH,O, »UsH;.CH,.CO. 
CH, CH, .CO,H, which crystallizes from hot water in long, thin 
Preiics, sities at 84°; the absence of an alcoholic hydroxyl is 
proved by the fact that ve ethyl ether is not attacked by heating 
with acetic anhydride. On heating with sodium amalgam and 

1 Pléchl, Ber. Deutsch. Chem. Ges. xiv. 1316. 


2 Fittig and Jayne, Ann. Chem. Pharm. cexvi. 115; Fittig and Ost, bid. 
ecxxvii. 61. 3 Ehrlich, zed. clxxxvii. 26, 


356 AROMATIC COMPOUNDS. 











water, it is converted into hydroxypiperhydronic acid, which 
separates from ether or hot water in lustrous crystals, melting at 
95°. On further heating or on boiling with water, it is con- 
verted into piperhydrolactone, C,.H,,0,, which is also formed 
when the acid is preserved in a desiccator. It is a clear, oily, 
tasteless and odourless liquid, which has the following 
constitution :} 


O 
CHC | Hy Ce HCH, 


O———CO 


DIHYDROXY-ACIDS, C,,H,,0. 


2479 Only the following derivatives of these bodies are 
known: 


O 
a-8-Dihydroxypiperhydronic acid, CHC C,H, CH, CH 
O 


(OH)CH(OH).CO,H, has been obtained by the action of potas- 
slum permanganate on @-hydropiperic acid. It is readily soluble 
in hot water and in alcohol, crystallizes in radiating groups of 
needles, melts at 165° and is converted by further oxidation into 
methylenehydrocaffeic acid. 


O 
B-y-Dihydroxypiperhydronie acid, CHC | >CiH, CH, CH 


(OH)CH(OH)CH,.CO,H, is formed by the oxidation of a-hydro- 
piperic acid with potassium permanganate in alkaline solution 
and is precipitated by acids as hydroxypiperhydrolactcne, which 
has the following constitution : 


CH.CH(OH)CH, 


O 
OH | Ou, CH Set 


This substance is only slightly soluble in water, readily in 
alcohol and separates on the addition of petroleum spirit to its 
solution in chloroform in long, lustrous needles, which melt at 
104°5°. If its solution in caustic potash be well cooled and 
acidified with dilute sulphuric acid, the dihydroxy-acid separates 


1 Fittig and Weinstein, Ann. Chem. Pharm. ccxxvii. 32. 


PHENYLBUTYLKETONE. 357 


out in fine, white crystals, which may be recrystallized from luke- 
warm water and melt at 123°, decomposing simultaneously into 
water and the lactone. It forms salts, which crystallize well and 
are very stable.! 


KETONES, C,,H,,0. 


2480 Phenylbutylketone, C,H,.CO.C,H,, is formed when 
propylbenzoylacetic ether, C,H,;.CO.CH(C,H,)CO,.C,H,, is 
boiled with alcoholic potash. It is an oily, aromatic smelling 
liquid, which boils at 256°—238°. 

Phenylisobutylketone, C,H,.CO.C,H,(CH,),, was obtained by 
Popow by the distillation of a mixture of calcium benzoate and 
calcium valerate,? while Perkin and Calman prepared it from 
the ether of isopropylbenzoylacetic ether. It has also a pleasant 
aromatic odour, boils at 227°—228° and is oxidized by chromic 
acid to benzoic acid, isobutyric acid and acetic acid. 

Aylylethylketone, (CH,),C,H,.CO.C,H,, is formed by the action 
of aluminium chloride on a mixture of paraxylene and propiony| 
chloride. It is a strongly refractive, aromatic smelling liquid, 
which has a sharp, bitter taste and boils at 237°—238°4 


DIKETONES, ©,,H,,0,. 


2481 Phenylacetylacetone, O,H;.CH,.CO.CH,.CO.CH,, is ob- 
tained when phenylacetylaceto-acetic ether, C,H,.CH,.CO.CH 
(CO,C,H,)CO.CH,, is boiled for some time with water. It is an 
oily liquid, which boils at 266°—269° and is tolerably soluble in 
hot water. Ifit be dissolved in dilute caustic soda and an excess 
of concentrated caustic soda solution added, the sodium salt 
separates out as a crystalline precipitate, while silver nitrate 
precipitates the compound C,,H,,AgO, from the ammoniacal 
solution in white flocks, which rapidly become violet coloured 
in the light.® 


1 Regel, Ber. Deutsch. Chem. Ges. xx. 414. 

2 Perkin and Calman, Journ. Chem. Soc. 1886, i. 161. 

3 Ann. Chem. Pharm. clxii. 153. 

* Claus and Fickert, Ber. Deutsch. Chem. Ges. xix. 3182. 
5 Fischer and Biilow, 7bid. xviii. 2136. 


358 AROMATIC COMPOUNDS. 


A cetophenone-acetone,C,H,.CO.CH,.CH,.CO.CH,,1s formed,when 
acetophenone-aceto-acetic ether, C,H,.CO.CH,.CH(CO,C,H;)CO. 
CH,, is boiled with dilute alkalis. It is a yellowish oily liquid, 
which decomposes on heating and is only slightly soluble in cold, 
more readily in hot water. 

Acetophenone-acetoxime, C,,H,,0(NOH), is obtained by the 
action of hydroxylamine on the diketone and crystallizes from 
dilute alcohol in long, white, lustrous needles, which melt at 
122°—123° and are soluble in both acids and alkalis.! If the 
ketone be heated with acetic anhydride or gently warmed with 
fuming hydrochloric acid, phenylmethylfurfuran, C,,H,,0, is 
formed, the ketone probably passing into the tautomeric alcohol, 
which then loses water : 


CH—=C(OH).CH, CH=C.CH, 
| Se er ate) 
CH=C(OH).C,H, CH=C.C.H, 


Phenylmethylfurfuran crystallizes from alcohol in long, 
lustrous needles, which have a faint odour of phenol and melt 
at 41°—42°. It boils at 235°—240° and is neither attacked by 
hydroxylamine nor acetyl chloride.2 It is converted by the 
action of sodium upon its alcoholic solution into phenylmethyltetra- 
methylene oxide, an oily, mobile liquid, which boils at about 230° 
and has the following constitution : 


CH,.CH.CH, 
pees 
CH,,.CH.C,H, 


KETONIC ACIDS. 


2482 Benzylaceto-acetic acid, CH,.CO.CH(CH;.C,H,)CO,H, is 
unknown in the free state. Its ethyl ether is formed by the 
action of benzyl chloride on sodium aceto-acetic ether and is a 
thick liquid, which has a faintly aromatic odour and _ boils 
at 276°.3 


1 Paal, Ber. Deutsch. Chem. Ges. xvi. 2865; xvii. 918. 

2 Ibid. xvii. 2756. 

3 Ehrlich, Ann. Chem. Pharm. clxxxvii. 12; Conrad'and Bischoff, zbid. cciv, 
180. 


BENZYLACETO-ACETIC ACID. 359 


Dimethylbenzoylacetic acid, (CH;),C,H,.CO.CH,.CO,H, has 
been prepared by the oxidation of paraxylylethylketone with 
potassium permanganate and is slightly soluble in water, readily 
in alcohol. It crystallizes from a mixture of petroleum ether 
and choloroform in fascicular groups of large needles, which 
melt at 132° (Claus and Fickert). 

Ethylbenzoylacetic acid C,H;.CO.CH(C,H,)CO,H, was obtained 
by Perkin, who dissolved 1:2 grams. of sodium in absolute 
alcohol, added 10 grams. of benzoylacetic ether to the cooled 
solution and boiled the mixture with 10 grams. of ethyl iodide. 
The ether thus obtained was saponified with cold alcoholic potash 
and the acid precipitated with dilute sulphuric acid. It forms 
crystals, which melt at 112°—115° with slight decomposition, and 
readily decomposes in an analogous manner to aceto-acetic ether 
pti p15)" 

The ethyl ether is a strongly refractive liquid, which has an 
aromatic odour and a burning taste, boils at 231°—232° at a 
pressure of 725 mm. and may be distilled at the ordinary pressure 
almost without decomposition when pure.” 

Benzylacetone-orthocarboxylic acid, CH,.CO.C,H,.C,H,CO,H, 
is obtained by heating the carboxylic acid of benzylaceto-acetic’ 
ether, CH,.CO.CH(CO,C,H,)CH,.C,H,.CO.H, with baryta water, 
and crystallizes in fine needles, which are readily soluble in water 
and alcohol and melt at 114°.° 

Phenyl-laevulimie acid, C,H,.CH(CH,.CO.CH,)CO,H, is formed, 
when the ether of phenylacetosuccinic acid,C,H,.CH(CH,.COCH. 
CO,H)CO,II, is boiled, and crystallizes from hot water in 
fascicular groups of pinnate plates, which melt at 126°. 

Benzoyltrimethylenecarboxylie acid, C,H;.CO.C,H,.CO.H. The 
ethyl ether is obtained by adding ethyl benzoylacetate to a 
solution of sodium in absolute alcohol and then treating the 
cooled solution with ethylene bromide, the mixture being finally 
heated on the water bath : 


CH,Br 00.0 
l + 20NaH¢ = 
CH,Br CO,.C,H, 


CH C0.0,H C0.0,H 
| are 6 5 ti CHK Ono 
Chi a NCOLGL EM CO,.0,H, 


1 Perkin, Ber. Deutsch. Chem. Ges. xvi. 2130. 

2 Perkin, Journ. Chem. Soc. 1885, i. 240. 

3 Biilow, Ann. Chem. Pharm. cexxxvi. 192. 

4 Weltner, Ber. Deutsch. Chem. Ges. xvii. 72 ; xviii. 790. 


289 


360 AROMATIC COMPOUNDS. 


The crude product is saponified with cold alcoholic potash and 
the acid separated by sulphuric acid and then purified by con- 
version into the sodium salt and reprecipitation. 

Benzoyltrimethylenecarboxylic acid is only slightly soluble in 
water and crystallizes from ether in splendid, monoclinic prisms. 
It can be boiled with alcoholic potash without undergoing de- 
composition. The ethyl ether is a thick, oily liquid, which has 
a faint aromatic odour and a burning taste and boils without 
alteration at 280°—283". 

The acid melts with decomposition at 148°—149° and 
decomposes at a slightly higher temperature into carbon dioxide 

CH, 
and benzoyltrimethylene C,H, CO.CHE | 
CH; 


This is an oily, aromatic smelling liquid, which boils at 2839°— 
239°5° and combines with hydroxylamine to form Jbenzoyl- 
trimethylene-oxime, O,H;.CCNOH)C,H,; this compound 
crystallizes from ether in well formed prisms, which melt at 
86°—87° and decompose after standing for some time with 
formation of a brown oil.} 

Benzoylaceto-acetic acid, C,H,.CO.CH(CO,H)CO.CH,. This 
diketonic acid is only known in the form of its ethyl ether, 
which is obtained by the action of benzoyl chloride on sodium 
aceto-acetic ether and is athick liquid, which has a faint aromatic 
odour, decomposes on distillation? and is resolved into carbon 
dioxide, acetic acid, acetophenone and benzoylacetone by boiling 
with water or alcohol.® 

Acetobenzalacetie acid or a-Acetocinnamic acid C,H;.CH=C 
(CO.CH,)CO,H. The ethyl ether is obtaimed by heating 
benzaldehyde with aceto-acetic ether and acetic anhydride. It 
distils as an odourless, strongly refractive, very thick liquid, 
solidifying after a short time to a macrocrystalline mass, 
which crystallizes from alcohol in very lustrous, transparent, 
four- or six-sided rhombic tablets. It melts at 59°—60° and 
boils at the ordinary pressure with slight decomposition at 295° 
—297°. A trace of this ether brought into sulphuric acid 
produces a light yellow solution, which becomes an opaque dark 
red on heating. If it be then poured into water, a yellow 
precipitate separates out, which forms a violet solution in 
caustic soda. 


1 Perkin, Jowrn. Chem. Soc. 1885, i. 836. 
* Bonné, Ann. Chem. Pharm, elxxxvii. 1; James, ibid. ecxxvi. 220. 
3 E. Fischer and Biilow, Ber. Deutsch. Chem. Ges. xviii. 2131. 


ACETOBENZALACETIC ACID. 361 





The ether is also formed when a mixture of benzaldehyde and 
aceto-acetic ether is saturated with hydrochloric acid at 0°. Two 
isomeric compounds, C,,H,,ClO,, are the first products; these 
decompose on distillation with elimination of hydrochloric acid 
and may be separated by crystallization from boiling petroleum- 
spirit. The one crystallizes in prisms, which melt at 40°—41°, 
the other in small rhombohedra or tablets, melting at 71°—72°, 
Both decompose in moist air. Their formation admits of a 
simple explanation. Benzidene chlorhydrin is first formed and 
acts upon the ether: 


OH CO.CH 
C,H, CHC + CHK “ea 
Cl CO,.C,H, 


Van 0.CH, 
C,H;.CHCI. MS + H,0. 
CO,.C,H, 
Hydrochloric acid is then eliminated and re-added, the 
isomeric compound being formed : } 


AOKH, CO.CH, 
C,H, CH=CC + HCl=0,H,.CH,.cak’ 
CO,.0,H, \co,.0,H, 


DIBASIC ACIDS. 
CO,H 
\ C(OH,),CO, H 


a solution of homophthalimide, caustic potash and methyl 
iodide in wood spirit is heated to 100°, dimethyl homophthali- 
mide is formed and has the following constitution : 


2483 Dimethylhomophthalic acid, OC, . When 


ig OCH CO 
6 SG 
CO—_NH 


This substance crystallizes from hot water in flat, foliaceous 
needles, melting at 119°—120°. On heating with fuming 


1 Claisen and Matthews, Ann. Chem. Pharm. cexviii. 176. 


362 AROMATIC COMPOUNDS, 


hydrochloric acid to 230°, the anhydride of dimethylhomophthalic 
acid is formed : 


C(CH,),CO /(CH,),CO 
Cuang Peo elizp Nee 
\co—_NH SCOnO 


This body separates from alcohol in flat crystals, which melt 
at 82°5°—83° and dissolve slowly in ammonia. On addition of 
ammonia, silver dimethylhomophthalate, C,,H,,Ag,O,, is precipi- 
tated as a viscid mass, which becomes granular on boiling." 

Methylbenzylmalonic acid, C,H,.CH,.C(CH,)(CO,H),, is formed 
by the action of methyl iodide on a solution of sodium and 
benzylmalonic ether in absolute alcohol. The ether thus 
obtained is a mobile liquid, which boils at 300° and is saponified 
by concentrated caustic potash solution. The free acid forms 
crystals, which melt at 135° and decompose at a higher tempera- 
ture into methylbenzylacetic acid and carbon dioxide. 

Benzoylpropionorthocarborylic acid, CO,H.C,H,.CO.C,H,.CO,H. 
When phthalic anhydride is heated with succinic acid and 
sodium acetate, the double lactone of this acid is formed : 


CH COM HCH e nC: 
| [+ | | = 
CO—O0  CO.0H CO0.0H 
oN, CH,.CH, 
ae OC Oe 
eos : ; 


It crystallizes from alcohol in fine, lustrous needles, melting at 
120°. On boiling with water, the acid is formed and remains on 
evaporation as a syrup, which has probably. the composition 
CO,H.C,H,.C(OH),.C,H,.CO,H, and is re-converted into the 
lactone by heating on the water bath. If it be extracted with 
ether and the solution diluted with petroleum-ether, the benzoyl- 
propionorthocarboxylic acid separates out in small, lustrous, six- 
sided prisms, which melt at 137°. Sodium amalgam converts it in 
alkaline solution into the acid, CO,H.C,H,.CH(OH)C,H,.CO,H 
which, however, loses water and changes into phthalidepropionic 
acid : 

C,H 
| * SCH.CH,CH,.CO,H. 
C0.0% 


1 Gabriel, Ber. Deutsch. Chem. Ges. xix. 2363. 


PHTHALYLPROPIONIC ACID. 363 


This substance crystallizes from hot water in nacreous plates, 
melting at 121° 

On heating the lactone with hydriodic acid and phosphorus, 
phenylbutyro-orthocarborylic acid, CO,H.C,H,.C,H,.CO.H, is 
formed and separates from the hot aqueous solution in small 
plates, melting at 138°—139°.? 

2484 Hydrindonaphthenedicarborylic acid, C,H, : C,H,(CO,H),. 
The ethyl ether is formed by the action of orthoxylylene 
bromide on a solution of sodium and malonic ether in alcohol: 


BAGH BE 
CoH + CH,(CO,.C,H,), = 
CH,Br 
CH. CO,.C,H 
GH Se i 4 SHB 


o CoH, 


The free acid crystallizes from water in rhombic plates or tablets, 
which melt at 199° and decompose at a slightly higher tempera- 
ture into carbon dioxide and hydrindonaphthenemonocarboxylic 
acid.’ ‘This is also formed when aceto-acetic ether is substituted 
for malonic ether in the above synthesis, and the acetyl deriva- 
tive which is formed decomposed with caustic potash : 


SOLE, 
C hie® ENG + 2KOH = 
ea Poo, C,H, 
eo GZ + KO.CO.CH, + C,H,.OH. 


BC oe coe 


It crystallizes from boiling water in fascicular groups of 
needles, which melt at 130° and are volatile without decom- 
position, It is oxidized by potassium permanganate to the acid 
C,H,(CO,H)CO.CO,H, which yields phthalidecarboxylic acid 
on reduction.* 

LACH )CO,H 
Phthalylpropronie acid, Bien , 1s obtaimed 


by boiling phthalic anhydride with sodium propionate and 


1 Roser, Ber. Deutsch. Chem. Ges, xvii. 2770. 

2 Roser, 2bid. xviii. 3115. 

3 Baeyer and Perkin, zbid. xvii. 122. 

4 Scherks, zbid. xviii. 378; Perkin, Journ. Chem. Soc. 1888, i. 7. 


364 AROMATIC COMPOUNDS. 


propionic anhydride, and crystallizes from alcohol in needles, 
melting at 245°—248°. It is converted into orthopropylbenzoic 
acid by heating with hydriodic acid, while boiling alkalis 
decompose it into carbon dioxide and propiophenonecarboxylic 
acid.? 

Phenylparaconic acid, C,,H,,0,, is formed, accompanied by a 
little isophenylerotonic acid, when benzaldehyde is heated with 
sodium succinate and acetic anhydride : 


CH,.CO.OH 0.08 
O,H,.CHO + | = O,H,.CH.CH 
CH,.C0.0H 1 SeRNCH: 
OH | 
6O.0H 


O———_CO 


The dibasic phenylitamalie acid is first formed, but decomposes 
immediately into water and its lactone, phenylparaconic acid. 
The latter crystallizes from hot water in long, lustrous needles 
of the formula, 4C,,H,,O, + H,O, which melt at 99°, lose their 
water and then melt at 109°. It combines in the cold with 
alkalis to form salts containing one equivalent of metal, while 
salts of phenylitamalic acid are obtained with hot solutions. 
These yield phenylparaconic acid on decomposition with acids. 
Phenylparaconic acid decomposes on dry distillation into carbon 
dioxide, phenylisocrotonic acid, phenylbutyrolactone and a- 
naphthol.” 

Benzoylsuccinie acid, C,H;.CO.CH(CO,H)CH,(CO,H). The 
ethyl ether is readily formed by the action of ethyl mono- 
chloracetate on sodium benzoylacetic ether : 


C,H;.CO.CHNa.CO,C,H, + CH,CLCO, CoH.’= 

7/2 C02, Cols 

Eric FAG OROinE + NaCl. 

\o,,0,H, 
It is a thick, pleasant-smelling, aromatic liquid, which boils at 

260°—265° at a pressure of 160 mm., and is coloured a fine 


1 Gabriel and Michael, Ber. Deutsch. Chem. Ges. xi. 1013. 
* Fittig and Jayne, Ann. Chem. Pharm. ecxvi. 97. 


BENZYLMALONORTHOCARBOXYLIC ACID. 365 


claret-red in alcoholic solution by ferric chloride. When it 
is boiled with baryta water, benzoic and succinic acids are 
formed, while carbon dioxide and benzoylpropionic acid are 
obtained by boiling with sulphuric acid. 

Benzoylisosuccinie acid, C,H;.CO.CH,.CH(CO,H),. The ethyl 
ether is obtained by the action of benzoylmethyl bromide on 
sodmalonic ether, and is a heavy, yellow, oily liquid. The free 
acid crystallizes from water in spherical masses of small needles, 
melts and froths up at 178°—179°, and decomposes at a slightly 
higher temperature into carbon dioxide and benzoylpropionic 
acid.? 


TRIBASIC ACIDS. 


2485 Benzylmalonorthocarboxylic acid, (CO,H),CHLCH,.C,H,. 
CO,H. The product of the action of phthalyl chloride on 
sodmalonic ether is phthalylmalonic ether : 


O,H CO,.C,H 
cog ; "SOCl, + 2NaCH At FS 
Hh. 


ad ert Wi 
BUS. © WG 
ag Co,.C,H, 


It crystallizes from ether in large, asymmetric prisms, which 
show a large number of faces, have almost a diamond lustre and 
melt at 745°. It solidifies when pure in exceedingly charac- 
teristic forms; if a small quantity be fused on a watch glass 
and allowed to cool, the liquid commences to solidify at isolated 
spots and aggregates are formed, which absorb the residual 
liquid, so that finally a number of isolated masses, shaped like 
sea anemones, are formed. 

The ether is decomposed by alkalis into malonic acid, phthalic 
acid and alcohol, while it yields diethyl benzylmalonorthocar- 
boxylate on heating with zinc dust and acetic acid. This 
substance gives on saponification benzylmalonorthocarboxylic 
acid, which crystallizes from hot water in small, lustrous, very 
brittle prisms, which melt at 170° with evolution of carbon 
dioxide and decompose completely at 190° into this and 
hydrocinnamocarboxylic acid. 


1 Perkin, Jowrn. Chem. Soc. 1885, i. 272. 
2 Kues and Paal, Ber. Dewtsch. Chem. Ges, xviii. 3323. 


CO,.C,H, 
CO,.0,H, Ors 


+ CH + 2NaCl. 





*\CO,.C.H, 


366 AROMATIC COMPOUNDS. 


Diethyl benzylmalonorthocarboxylate, (CO,C,H,),CH.CH,.C,H,. 
CO,H, which has been termed benzylmalonic-ether-orthocarboxylic 
acid by Wislicenus, is extremely soluble in ether, freely in alcohol 
and tolerably in hot water, from which it crystallizes in hair-like, 
pliable needles, melting at 86°. 

It is a monobasic acid; its silver salt is energetically acted 
upon by ethyl iodide with formation of triethyl benzylmalonortho- 
carboxylate, (C,H,.CO,),CH.CH,.C,H,.CO,.C,H;, which is a 
thick, colourless liquid, and boils at 250° at a pressure of 45 mm.1 

Phenylearboxysuccinie acid, C,H;.CH(CO,H)CH(CO,H),, is 
formed by the action of ethyl phenylchloracetate on sodium 
malonic ether and the saponification of the product. It forms 
readily soluble crystals and decomposes on heating into phenyl- 
succinic acid and carbon dioxide.” 


ACIDS OF THE COMPOSITION, C,H,.C,H,.CO,H. 


GHeCH, 
2486 Phenylangelic acid, C,H, CH=CC 
CO.OH 
tained by Perkin by heating benzaldehyde with butyric anhydride 
and sodium butyrate to 180° It is also formed when acetic 
anhydride is employed and the temperature not allowed to rise 
above 100°; at a higher temperature cinnamic acid is formed, 
the amount of this increasing with the temperature reached.* 
Phenylangelic acid is only slightly soluble in water and separ- 
ates from alcohol in compact, transparent crystals, which melt 
at 104°. Its chloride is a yellowish liquid, which is converted 
by ammonia into phenylangelamide, C,H,.CH—C(C,H,)CO.N H,. 
This crystallizes from hot alcohol in prisms, melting at 128°. 
Cinnamenylpropionie acid, C,H,.;CH—CH.CH,.CH,.CO,H, 
was prepared by Perkin,® who named it hydrocinnamenylacrylic 
acid, by the action of water and sodium amalgam on cinnamenyl- 
acrylic acid (p. 369). It is precipitated from solution in alkalis by 
hydrochloric acid as an oil, which solidifies in a freezing mixture, 
or at the ordinary temperature in contact with a portion of the 


, was ob- 


1 Wislicenus, Ann. Chem. Pharm. ecxlii. 23. 

? Spiegel, zbid. ccxix. 32. 

3 Journ. Chem. Soc. 1877, i. 398. 

4 Fittig and Slocum, Ann. Chem. Pharm. cexxvii. 53. 
5 Journ. Chem, Soc. 1877, i. 405. 


HYDROPIPERIC ACIDS. 367 





previously solidified acid, and crystallizes in large plates, which 
melt at 28°—29°1 It combines with bromine and hydrobromic 
acid, is not acted upon by sodium amalgam and is reduced to 
phenylpentylic acid by heating with hydriodic acid. 


O 
a-Hydropiperic wid OH | CHyCHy CH=CH.CH,C Oe) 


was obtained by Foster, who dissolved piperic acid in caustic 
potash, heated the solution on the water bath with sodium 
amalgam and added hydrochloric acid from time to time? It 
was then further investigated by Fittig in conjunction with 
Mielk,2 Remsen, and Buri.6 The latter obtained an isomeric 
acid by this means which had not been previously observed, and 
which is only formed when the solution is kept strongly alkaline ; 
sufficient hyrochloric acid must therefore be added in the pre- 
paration of the a-acid to keep the solution always faintly alkaline. 
The pure compound forms large, well developed crystals, which 
melt at 78°, and are slightly soluble in water, readily in alcohol. 
It is not further reduced by sodium amalgam and water, but 
combines with bromine to form dabromopiperhydronie acid, CH, 
—0,.C,H,.CH,.CHBr.CHBr.CH,.CO,H, which separates from 
benzene in crystals, melting at 140° Potassium permanganate 
oxidizes a-hydropiperic acid to piperonal, piperonylic acid and 
hydroxypiperhydrolactone (p. 356). 


0 
ee reomiert acid, CHC CH, CH,,CH,.CH=CH.CO,H, 
0 


is not only formed as described above, but also when the 
a-acid is heated with caustic soda for some time. A hydroxy- 
piperhydronic acid is probably first formed, in an analogous 
manner to the formation of hydracrylic acid from acrylic acid, but 
this loses water at the moment of liberation from its sodium salt 
and the position of the double linking is thus changed (Fittig and 
Weinstein) : 


O 
CHC | >O\H, OH, CH, CH(OH)CH, CO,H s 


Dao 
CH _ C,H, CH,,CH, CH=CH.CO,H + 1,0. 
O 


1 Baeyer and Jackson, Ber. Deutsch. Chem. Ges, xiii. 122. 
2 Ann. Chem. Pharm. exxiv. 115. 3 Ibid. clii. 56. 
4 Ibid. clix. 160. 5 Ibid. ccxvi. 171. 


6 Fittig and Weinstein, ibid. ccxxvii. 33. 


368 AROMATIC COMPOUNDS. 


It crystallizes from alcohol in needles, melting at 131°, and 
combines with hydrogen to form piperhydronic acid (p. 351), 
but does not combine with bromine, which only yields substitu- 
tion products. It is oxidized to dihydroxypiperhydronic acid by 
potassium permanganate (p. 356). 

Bromo-8-hydropiperte acid, CH,O.C,H,Br.C,H,.CO,H, cry- 
stallizes from benzene in small, striated plates, melts at 170° 
—171° and is converted into bromomethylhydrocaffeic acid by 
potassium permanganate. 


O 
Methylenedioxyphenylangelic avid, CHK ye gH,- CH—=0(C,H) 
O 


CO,H, is formed when piperonal is boiled with butyric anhydride 
and sodium acetate. It crystallizes from alcohol in long, matted 
needles.1 


COUMARINS, C,,H ,0,. 


CH—C—C,H, 
2487 Hthylcoumarin, C, oH | , was obtained by 
O CO 
Perkin, who named it butyric-acid-coumarin by heating sodium 
salicylaldehyde with butyric anhydride. It forms monosym- 
metric crystals, which smell like coumarin, melts at 70°—71’, 
boils at 299° with slight decomposition and is converted by 
boiling with caustic potash into butyrocowmarie acid, C,H,(OH) 
CH—C(C,H,)CO.H, which crystallizes from dilute alcohol in 
flat prisms and melts at 174° with decomposition.? 
U( CH.) CR 
Dimethyleowmarin, SIRES TASS: | ,1s formed by the 
0 ——— CO 
action of sulphuric acid on a mixture of paracresol and aceto- 
acetic ether and crystallizes from dilute alcohol in long, strongly 
refractive needles, melting at 148°.° 





Dimethyleowmarilic acid, CH3.C mK So. CO,H, is obtained 


by the action of hot, alcoholic potash on bromodimethyleoumarin 
(p. 246). It crystallizes from alcohol in short prisms or tablets 
1 Lorenz, Ber. Deutsch. Chem. Ges. xiv. 785. 
2 Ann. Chem. Pharm. ex\vii. 238; cl. 84; Journ. Chem. Soc. 1881, i. 439. 


* von Pechmann and Duisberg, Ber. Deutsch. Chem. Ges. xvi. ‘2119 ; von 
Pechmann and Cohen, ibid. xvii. 2187. 


HYDROXYCOUMARINS. 369 


which melt at 224°—225°, Its ethyl ether is analogous to that 
of the dimethylcoumarilic acid (p. 332), which has been prepared 
from paracresol and ethyl monochloraceto-acetate, melts at 55° 
and boils at 298°—300°.} 


HYDROXYCOUMARINS, (C,,H,,0.. 


/ECH)=C.CH, 

2488 Dimethylumbelliferon, See oe 4 | poms 
O CO 

formed by the action of sulphuric acid on a mixture of 
resorcinol and methylaceto-acetic ether. It crystallizes from 
wood-spirit in needles, which have a very high refractive index 
and melt at 256°. Its solutions in sulphuric acid and the alkalis 
are almost colourless, but show a distinct blue fluorescence? 


C(CH,)—CH 
é. ; | , has 
No 


been prepared from orcinol and aceto-acetic ether, and crystal- 
lizes from alcohol in needles, which melt and partially sublime 
at 248°—250°. It forms yellow, nonfluorescent solutions in 
sulphuric acid and the alkalis. 





Homomethylumbelliferon, CH,.C,H,(OH) 





ACIDS, C,H, C,H,CO,H. 


2489 Phenylbutinylcarboxylic acid, C,H,CH—CH.CH—CH. 
CO,H, was obtained by Perkin, who named it cinnamenylacrylic 
acid, by boiling cinnamaldehyde with sodium acetate and acetic 
anhydride When a mixture of cinnamaldehyde, malonic acid 
and glacial acetic acid is heated, phenylbutinedicarboxylic acid, 
C,H,CH—CH.CH—C(CO,H),, is formed. This substance 
crystallizes in needles and decomposes on heating to 210° into 
carbon dioxide and phenylbutinylcarboxylic acid.® Acetone 
condenses with cinnamaldehyde in presence of dilute caustic 
soda solution to form phenylbutinylmethylketone, which crystallizes 

1 Hantzsch and Lang, Ber. Dewtsch. Chem. Ges, xix. 1298. 


9 


2 y, Pechmann and Duisberg, ibid. xvi. 2127. 

3 y, Pechmann and Cohen, 77d. xvii. 2189 ; Cohen, Jnaugur.-Dissert., Munich, 
1884. 

4 Journ. Chem. Soc. 1877, i. 403. > Stuart, ibid. 1886, i. 365. 


370 AROMATIC COMPOUNDS. 


in rhombic tablets, melting at 68°, and decomposes on heating 
with an alkaline solution of sodium hypochlorite into chloroform 
and the acid :! 
C,H,.CH—CH.CH—CH.CO.CH, + 3ClOH = 
C,H;.CH—CH.CH—CH.CO,H + CHCl, + 2H,0. 


It crystallizes from alcohol, or better from petroleum ether, 
in thin tablets, melting at 166°. 

Piperic acid, C,,H,,O,, was discovered by v. Babo and Keller, 
who found that the piperine which is contained in pepper, decom- 
poses on boiling with alcoholic potash into piperic acid and the 
volatile, strongly basic piperidine, the reaction proceeding 
according to the following equation (Strecker) :* 


C,,HjyNO; + HO = C,.H,,0, + C5H,,N. 


Piperic acid is almost insoluble in water and crystallizes from 
hot alcohol in long, yellowish, matted needles, which melt at 
216°—217° and sublime with partial decomposition at a slightly 
higher temperature. The constitution of this body has only been 
very gradually ascertained. Strecker found that the acid is 
monobasic and is decomposed by fusion with caustic potash into 
protocatechuic acid, oxalic acid and acetic acid,® while Foster 
showed that it combines with hydrogen to form hydropiperic 
acid, which is also monobasic (p. 367). -Fittig and Mielck then 
proved that the two oxygen atoms, which are present in addition 
to those of the carboxyl group, are not contained in the form of 
hydroxyl, methoxyl or an homologous group. It is converted 
by oxidation with potassium permanganate into piperonal and 
piperonylic acid, the investigation of which led to the following 
formule, which were subsequently confirmed by the synthetical 
preparation of the > TO in question :® 


O 
jcae , CO,H 
It was further observed that piperic acid combines with four 


atoms of bromine, and the following constitution was therefore 
ascribed to it: 


aN 
BC > CgHy CH=CH.CH=CH.CO,H. 
1 Diehl and Einhorn, Ber. Deutsch. Chem. Ges. XViii. 2324. 
2 Jahresber. Chem. 1857, 413. 3 Ann. Chem. Pharm. ev. 217. 
4 Fittig and Mielck, cbid. clii. 25. 5 Tbid. exviii. 250. 


6 Fi ittig and Remsen, ibid. clix. 129; clxviii. 93. 


PIPERIC ACID. 371 


Since, however, the constitution of a-hydropiperic acid has now 
been ascertained with considerable accuracy, the formula given 
above must be rejected. . It is known that acids of this class, such 
as 8-hydropiperic acid for example, combine more readily with 
hydrogen the nearer the double linking is to the carboxyl group, 
and the constitution of piperic acid is therefore most probably 
represented by the formula: 


Waa 
aes cls CH, CH—C—CH.CO,H. 


Hihyl piperate, (CH,O,)C,H,.C,H,.CO,.C,H,, is formed when 
piperic acid is heated with ethyl iodide and caustic potash. It 
crystallizes from alcohol in large, yellowish, transparent, lustrous 
plates, melting at 77°—78°. 

Tetrabromopiperhydronie acid, (CH,O,)C,H,.C,H,Br,.CO,H, is 
obtained by the action of bromine on piperic acid in presence of 
carbon disulphide, and is a crystalline powder, which melts at 
160°—165° and decomposes energetically at the same time. 
On boiling with water or on dissolving in cold sodium carbonate 
solution, dibromopiperinide, C,,H,Br,O,, is formed, which crystal- 
lizes from dilute alcohol in lustrous prisms, melting at 136°, and 
is converted by boiling with sodium carbonate solution imto 
bromohydroxypiperinide, C,,H,BrO;. This substance separates 
from alcohol in monosymmetric crystals and decomposes on 
further boiling with alkalis with formation of piperonal The 
constitution of these compounds is probably expressed by the 
following formule : 


Dibromopiperinide. 
CHC | Osi CH, CH.CBr=CBr 
O————-CO 


Bromohydroxypiperinide. 


0 

cH) SC.H..CH,.CH.CBr—. 
C Kt CH, CH.CBr CoH 
Geb Ci) 


1 Fittig and Mielck, Ann. Chem. Pharm. clxxii. 134. 


372 AROMATIC COMPOUNDS. 


INDOL DERIVATIVES CONTAINING ELEVEN 
ATOMS OF CARBON. 


2490 Pr2-3-Methylethylindol, C Aa SS CCH, is formed 


when methylpropylketone hydrazone is aie with zine chloride, 
and is an oily liquid, which boils at 291°—293°. Its picrate 
crystallizes from benzene in fine, dark red needles. 
Acetylmethylketol is obtamed when methylketol is heated with 
sodium acetate and acetic anhydride, in a similar manner to 


pseudo-acetylpyrrol he Lip, BLD 


CO.CH, 
C,H, Vis cave CH, + 0 Hs 
*\NH \cO.CH, 


£000, 
‘SsC.CH, + HO.CO.CHG. 


oA NH Pal 
It crystallizes from benzene in colourless needles, melting at 
195°—196°, and forms a hydrazone.! 


_/ PCH .CO,H. 
Pr2-3-Methylindolacetie acid, C HA WE SsC.CH, _ , has been 


obtained from levulinic acid hydrazone ar is sightly soluble 
in hot water, readily in alcohol. It separates from acetone in 
crystals, which show a large number of faces, melt at 195°—200° 
with energetic evolution of carbon dioxide and decompose com- 
pletely on heating into this and Pr2-3-dimethylindol (p. 340). 
It does not give the pine-wood reaction, but forms a picrate, 
which crystallizes in dark red needles. 


C—CH,.CO,H 


Pr\®-2-3-Dimethylindolacetic acid, C,H, CCH, , 


Ane 
has been prepared from methylphenylhydrazine art levulinic 
acid, and crystallizes in fine, colourless plates, which melt at 
about 180° and decompose when more strongly heated into 
carbon dioxide and Pr1®—2-3-trimethylindol. The picrate forms 
red, feathery aggregates. 


1 Jackson, Ber. Deutsch. Chem. Ges. xiv. 879 ; E. Fischer, Ann. Chem. Pharm. 
cxlii. 378. 2 Degen, bid. ccxxxvi. 151, 


MELLITENE GROUP. 373 


MELLITENE GROUP. 


2491 ‘The first compound of this group which was known to 
chemists was mellitic acid, and the corresponding hydrocarbon 
was, therefore, named mellitene. 


HYDROCARBONS, (,.H,,, AND THEIR 
DERIVATIVES. 


HEXMETHYLBENZENE OR MELLITENE, C,(CH,),. 


This substance was first obtained by Hofmann, together with 
other products, by heating trimethylphenylammonium iodide to 
330° He also found that it is formed when xylidine hydro- 
chloride is heated to 250°—300° with wood-spirit.2 Lebel and 
Greene obtained it in small quantity, accompanied by other 
products, by heating wood-spirit strongly with zinc chloride, and 
the latter chemist prepared it in the same way from acetone.? It 
was prepared in larger quantity by Crafts and Friedel by the 
action of methyl chloride on a mixture of aluminium chloride 
and benzene or toluene. The polymerization of crotonylene, 
CH,.C=C.CH,, to hexmethylbenzene, which is brought about 
by agitation with sulphuric acid, is especially interesting? Its 
formation from durene has already been mentioned (p. 348). 
It is remarkable that both mellitene and trichloromesitylene are 
formed when methyl chloride is passed into a heated mixture of 
orthodichlorobenzene and aluminium chloride. The chlorine is 
probably replaced by the aluminium chloride residue and then 

1 Ber. Deutsch. Chem. Ges. v. 720. 
2 Ibid. xiii. 1729. 
3 Compt. Rend. \xxxvi, 260 and 930, 


4 Ann. Chim. Phys. [6] i. 459. 
5 Ber. Deutsch. Chem. Ges. xiv. 2073. 


374 AROMATIC COMPOUNDS. 


forms substitution products with the mesitylene which is also 
formed in the reaction.1 

Mellitene is readily soluble in hot alcohol and crystallizes in 
flat prisms or rhombic tablets, melts at 164°, boils at 264°, and, 
since it does not form a sulphonic acid, is insoluble in sulphuric 
acid. It can therefore be readily separated from pentamethyl- 
benzene. On heating to 200° with aluminium chloride, penta- 
methylbenzene, durene, isodurene, mesitylene, pseudocumene, 
metaxylene and very small quantities of toluene and benzene 
are formed, these being obtaimed in larger amount when 
hexmethylbenzene is heated with aluminium chloride im a 
current of hydrochloric acid.? 

It combines with picric acid to form the compound 
C,(CH;), + C,H,(NO,),0, which crystallizes in golden yellow 
flakes, melting at 168°—169°. 

Mellitone hexchloride or heachloromellitene, C,(CH,Cl),, is formed 
when the hydrocarbon is heated with phosphorus pentachloride. 
It crystallizes in flat, hexagonal tablets and melts and partially 
sublimes at 269°. When it is boiled with very dilute caustic 
soda solution, the chlorine is gradually removed and a substance 
is formed which melts at 180° and yields an aqueous solution, 
which has a very bitter taste. An isomeric compound is also 
formed in the preparation of hexchloromellitene; it melts at 
147° and probably has the formula C,(CH,),(CH,Cl),CCl,.? 

Mellitone heabromide or hexbromomellitene, C,(CH,Br),, is 
formed when mellitene is heated to 115°—120° with bromine 
and a little water, and is insoluble or only slightly soluble in 
most solvents. It crystallizes from ethylene bromide in rhombic 
tablets, which melt at 255°.4 


MELLITIC ACID, C,(CO,H),. 


2492 This acid was discovered in the year 1799 by Klaproth, 
who obtained it by boiling honeystone with water for a con- 
siderable length of time, and named it honeystone acid. He 
compared it with the vegetable acids, but was naturally unable 


1 Friedel and Crafts, Ann. Chim. Phys. [6] x. 411. 

2 Jacobsen, Ber. Deutsch. Chem. Ges. xviii. 338. 

3 Colson, Bull. Soc. Chim. xlvi. 197. 

4 Hofmann, Ber. Deutsch. Chem. Ges. xiii. 1729 ; Friedel and Crafts, Ann. 
Chim. Phys. [6] i. 468. 


MELLITIC ACID. 375 


at that early date to determine its nature. We owe to him, 
however, an experiment, which guided a later investigator to 
this end. He submitted honeystone, which is the aluminium 
salt of mellitic acid and occurs in seams of brown-coal, to dry 
distillation and obtained, together with carbon dioxide and a 
gas, which must have been carbon monoxide, a large quantity 
of water, which had simultaneously a pleasant, flowery odour 
and one of bitter almonds, and a drop of oil, which had a similar 
but fainter odour. 

The honeystone acid (acide mellitique) was then investigated 
by Vauquelin, but Wohler observed that this chemist had 
mistaken the acid potassium salt for the acid, and _ that 
Klaproth’s acid had been rendered impure by the presence of 
alumina. He prepared the pure compound and found that it 
decomposes on heating and yields a crystalline sublimate, 
without producing an empyreumatic odour like other organic 
acids, but resembles oxalic acid in its other properties. Accord- 
ing to him, honeystone contains a trace of a characteristic, 
apparently resinous substance, which was also noticed by 
Klaproth ; this is the cause of the aromatic smell produced 
when honeystone is burnt and is contained in all the salts 
prepared from it.1 Liebig and Wohler determined the formula 
for honeystone as C,H,O, and believed that it might possibly 
be formed from succinic acid, which also occurs in brown-coal. 
They even attempted to convert succinic into mellitic acid by 
the action of chlorine, an experiment which, occurring at that 
early period, is of special interest : ” 


C,H,0, + 4Cl = C,H,0, + 4HCL 


Erdmann, who found that mellitic acid is converted into 
pyromellitic acid by heating, observed that a characteristic spicy 
odour, resembling that of coumarin and oil of Spirza, is pro- 
duced when the salts of mellitic acid are heated. He there- 
fore heated a considerable quantity of the copper salt and 
obtained a solid substance and a liquid, which smelt like oil of 
bitter almonds or oil of cinnamon, and which he compared with 
the products obtained by the distillation of copper benzoate and 
copper salicylate by Ettling and Stenhouse. By the distillation 
of calcium mellitate, he only obtamed a small quantity of an 
aromatic vapour. 


1 Pogg. Ann, vil. 325. ? Ibid. xviii. 161. 
290 


376 AROMATIC COMPOUNDS. 





The analysis of the substances mentioned above proved 
that they contained hydrogen; since however this element 
is not present in the dried, anhydrous mellitates, the de- 
composition, which occurs when these salts, which are difficult 
to prepare in the anhydrous state, are heated, is “one in which 
both the elements of mellitic acid and of water take part.” } 
These results obviously show that aromatic substances are 
formed when mellitic acid is decomposed by heat, but these were 
only obtained in small quantity by Erdmann because sufficient 
hydrogen was not present. Baeyer therefore heated the acid 
with soda-lime and obtained a considerable quantity of benzene. 
He says on this point : “ According to the formula C,H,O,, which 
was then universally accepted, I had to await the evolution of 
acetylene, just as ethyl hydride is obtained by igniting succinic 
acid with lime: 

CT Oe rl enea)s 
ClO Rt oe 


“When I obtained benzene, I at first thought that a condensa- 
‘tion of the acetylene had taken place at the high temperature 
employed, this having been recently observed by Berthelot, when 
this gas is kept at a red-heat for some time. If this had been 
the case, mellitic acid ought to have yielded an isomeride of 
fumaric or succinic acid on reduction : 


CHO tHe CH OF 


4°74 
CEO oe a Oe 

“On treatment with sodium amalgam, however, mellitic acid 
was converted into an acid, which did not volatilize on heating, 
but carbonized like sugar and at the same time produced a 
smell.of burnt sugar. Mellitic acid must, therefore, have a much 
more complicated composition than had hitherto been believed, 
and it appeared probable that the products of its decomposition 
with soda-lime are not formed by condensation but are rather 
portions of a single molecule. According to this view, the 
simplest formula for mellitic acid is C,,0,,H, and it is a 
benzene in which all the hydrogen atoms have been replaced 
by carboxyl groups, CO.OH. The formula C,(CO,H), shows its 


analogy to benzoic acid, and its decomposition on heating with 


1 Journ. Prakt. Chem. lii. 482. 


MELLITIC ACID. 377 





lime corresponds exactly to the decomposition of benzoic acid 
into carbon dioxide and benzene : 


C,H,(CO,H) = C,H, + CO, 
C,(CO,H), = C,H, + 6CO,. 


“Tt is, further, the final member of a series of acids, several of 
which are already known, the so-called aromatic acids, which 
arise through the displacement of one or more hydrogen atoms 
in benzene by carboxyl.” } 

The line of investigation to pursue with respect to mellitic acid 
was thus indicated. All these acids, which have already been 
described, should be obtained in succession by the gradual elimina- 
tion of carbon dioxide, and, with the exception of benzenepenta- 
carboxylic acid, this proved to be the case. The observations of the 
earlier investigators were now fully explained. Baeyer repeated 
Klaproth’s experiment and states that the smell produced can 
easily be identified with that of the benzene obtained by dis- 
tilling benzoic acid with lime, which is always mixed with oil of 
bitter almonds, diphenyl and probably other bodies. The pro- 
ducts which Erdmann obtained also consisted of a mixture of 
benzene with aldehydes or ketones, which could not be formed 
if absolutely anhydrous salts of mellitic acid were employed, 
since these undergo the following decompositions : 


C,,0,,Cu, = 3Cu + 12CO 
C,,0,,Ca, = 3CaCO, + 3CO + 6C 
C,,0,,Al, = Al,O, + 9CO + 3C. 


The formation of mellitic acid from wood charcoal and other 
kinds of amorphous carbon, which was discovered by Schulze, is 
especially remarkable. If these be oxidized with an alkaline 
solution of potassium permanganate, oxalic and mellitic acids? 
are obtained in considerable quantity, together with other pro- 
ducts. They are also formed in small quantity, accompanied 
by hydromellitic acid and pyromellitic acid, when a current of 
electricity is passed through a solution of caustic potash between 
carbon poles,’ a fact which renders it possible that the benzene 
ring is contained in amorphous carbon. Mellitic acid is perkaps 
formed in nature by the oxidation of brown-coal. Friedel and 


1 Ann. Chem. Pharm. Suppl. vii. 1. 
2 Ber, Deutsch. Chem. Ges. iv. 802 and 806. 
3 Bartoli and Papasogli, Gaz. Chim. Ital. xiii, 37. 


378 AROMATIC COMPOUNDS. 


Crafts obtained it by oxidizing hexmethylbenzene with alkaline 
potassium permanganate. In order to prepare mellitic acid, 
Wohler brought the finely powdered honeystone into a solution 
of ammonium carbonate, which was thus decomposed with 
evolution of carbon dioxide, boiled the solution until the excess 
of ammonia was removed, filtered off the hydrated alumina and 
allowed the ammonium mellitate to crystallize out. The pure 
salt was then dissolved in water and precipitated with lead 
acetate, the precipitate being well washed, suspended in water 
and decomposed by sulphuretted hydrogen. According to 
Erdmann and Marchand, the lead precipitate always contains 
ammonia, and in order to obtain an acid quite free from 
ammonia it is necessary to boil the ammonium salt with baryta 
and decompose the barium salt with sulphuric acid! If the 
original honeystone be black and earthy, it must be digested for 
a considerable time with concentrated ammonia at a gentle heat, 
and the liquid finally heated to boiling and filtered off. The 
dark coloured filtrate is then evaporated to dryness and the 
residue heated for several hours to 120°—130°. Boiling water 
then extracts pure acid ammonium mellitate, to which Wohler’s 
method can subsequently be applied.? 

' Mellitic acid has a strongly acid taste, is extremely soluble in 
‘water and remains on evaporation as an indistinct crystalline 
powder. It is also readily soluble in alcohol and crystallizes on 
evaporation in stellate groups of fine needles. It is not attacked 
by boiling sulphuric acid, concentrated nitric acid, chlorine, 
bromine or hydriodic acid. On dry distillation it decomposes 
into carbon dioxide and _ pyromellitic acid, C,H,(CO,H),, 
while on heating with glycerol, it yields trimesic acid, C,H, 
(COE). 

2493 Its salts have been chiefly investigated by Erdmann and 
-Marchand, as well as by Kamrodt.2 They are very numerous, 
since mellitic acid is hexbasic, and their constitution was first 
explained by Baeyer. 

Normal potassium mellitate, C,,0,,K, + 9H,O, forms large, 
rhombic crystals, which readily effloresce. The acid salt, 
C,,0,,H,K, + 6H,O, crystallizes in large, rhombic prisms, which 
lose their water and become milk-white at a gentle heat. 
‘Wohler, by the addition of nitric acid to a solution of the 


1 Journ. Prakt. Chem. xliii. 129. ; 
2 Claus, Ber. Deutsch. Chem. Ges. x. 560. 
3 Ann. Chem. Pharm, 1xxxi, 164. 


MELLITIC ACID. 379 


normal salt, obtained a precipitate resembling cream of tartar, 
which he considered to be the acid salt. It is however a double 
salt, C,,0,,H,K, + NO,K, and crystallizes from hot water in 
irregular six-sided prisms. 

Normal ammoniwm mellitate, C,,0,(NH,), + 9H,O, is iso- 
morphous with the potassium salt; the acid salt, C,,0,,H, 
(NH,), + 4H,0, crystallizes in rhombic prisms. 

Barwm mellitate, C,,0,,Ba, + 3H,O, is precipitated in fine 
needles, when dilute solutions of ammonium mellitate and a 
barium salt are mixed. After drying it forms a silvery, foliaceous 
mass, which is only very slightly soluble in water. . 

Stlver mellitate, C,,0,,Ag,, 1s a crystalline precipitate, which 
only decomposes at above 130°. 

The mellitates of most of the metals are obtained as slightly 
soluble or insoluble precipitates. If the ammonium salt be 
precipitated with copper sulphate, the salt, C,,0,,Cu,(NH,),, 
separates out in sky-blue, microscropic crystals. 

Aluminium mellitate, C,,0,,Al, + 18H,O, occurs as honeystone 
or mellite in brown coal seams and forms in the pure state honey- 
yellow, transparent quadratic pyramids, which have a fatty 
lustre. It generally contains a small percentage of iron and is 
also found more or less darkly-coloured and as a black, earthy 
mass. 

Methyl mellitate, C,,0,.(CH;),, has been obtained by Kraut by 
the action of methyl iodide on silver mellitate,t while H. Miller 
prepared it by heating wood-spirit with mellityl chloride? It 
separates on the addition of water to its alcoholic solution in 
small lustrous plates, melting at 187°.° 

Lithyl mellitate, C,,0,.(C,H;),, forms rhomboidal crystals, which 
melt at 73° (Kraut and Busse). - 

Mellityl chloride, C,(COC1),, is formed when the acid is heated 
with phosphorus pentachloride and crystallizes from ether or 
benzene in hard, vitreous prisms, which melt at 190° and sublime 
in small plates at about 240°. It is only slowly decomposed by 
boiling water (Baeyer ; Claus). 

Imido-compounds of mellityl. By heating ammonium mellitate, 
Wohler obtained paramide, CJ,HNO,, together with the am- 
monium salt of euchronic acid, C,,H,N,O,, to which he gave 
this name because it is converted by reduction into a deep blue 


1 Jahresber. Chem. 1862, 281. 
2H. Miiller, Kekwlé’s Lehrb. ii. 405. 
3 Kraut and Busse, Ann. Chem. Pharm. clxxvii. 273. 


380 AROMATIC COMPOUNDS. 


substance, ewchron.1 Schwarz then found that, when the freshly 
prepared solution of paramide in ammonia is decomposed 
with hydrochloric acid, paramidic acid, C,,H;N;O,, is pre- 
cipitated.? 

The constitution of these compounds was quite unknown 
until Baeyer had explained that of mellitic acid : 


Paramide. Euchronic acid. Paramidic acid. 
CO CO.0H ~~ (C0.0H 
Gor NH GO GO 
GO Goo NH Gor Nt 
c. / COS NH C 7 
6 CO 6) GO 5) C0 
[co Go> NH Goo NH 
COs C0.0H CO.NH, 


Paramide or Mellitimide forms a white, tasteless and odourless 
mass, which on trituration with water takes the smell and 
consistency of moist clay (Wohbler). It is insoluble in water, 
alcohol and aqua regia, and dissolves without decomposition in 
sulphuric acid. Jt is converted by alkalis into euchronic acid 
and mellitic acid, the latter of which is also formed when it is 
heated to 200° with water. 

Argentammonium mellitimide, C,(CO),(NAgNH,)., 1s obtained 
as a precipitate when silver nitrate is added to a freshly 
prepared solution of paramide in ammonia. It dries to a yellow 
mass. 

EHuchronie acid or Mellitiminie acid is very difficultly soluble 
in water and crystallizes from hot, dilute hydrochloric acid in 
small, four-sided prisms, which taste like cream of tartar. When 
its solution is treated with zinc, the deep-blue coloured euchrone 
separates out. It forms a splendid purple-coloured solution in - 
alkalis and rapidly reoxidizes to euchronic acid in the air. Its 
composition is unknown, but, owing to the ease with which it is 
formed, it serves as a delicate test for the presence of mellitic 
acid. When euchronic acid is heated with water to 200°, it is 
converted into acid ammonium mellitate. 

Paramidic acid or Amidomellitiminic acid is a snow-white, 
crystalline powder, which is only slightly soluble in hot water, 
gives the euchrone reaction with zinc and is gradually converted 
into mellitic acid in ammoniacal solution. 

fTydromellitre acid, C,A,(CO,H),, is readily formed by the 
action of sodium amalgam and water on ammonium mellitate. 


1 Ann. Chem. Pharm. xxxvii. 268. 2 Ibid. lxvi. 46. 


s-TRIETHYLBENZENE. 381 


In order to prepare the acid from the product thus obtained, 
acetic acid is added, the solution precipitated with lead acetate 
and the precipitate decomposed by sulphuretted hydrogen. The 
hydromellitic acid remains on evaporation as a syrup, which 
gradually solidifies to indistinct crystals. It is strongly acid, 
melts on heating, then becomes brown and evolves carbon 
dioxide and finally decomposes with carbonization and evolution 
of fumes, which smell like the products which pass over last 
in the dry distillation of citric acid. It is scarcely attacked 
by oxidizing agents or a mixture of nitric and sulphuric acids. 
On heating with sulphuric acid, trimesic acid, prehnitic acid, 
mellophanic acid and prehnomalic acid are formed (p. 282). 
Isohydromellitic acid, C,H,(CO,H),, is gradually formed when 
hydromellitic acid is preserved, and more rapidly when it is 
heated to 180° for several hours with strong hydrochloric acid. 
It is tolerably solublein water and crystallizes in hard, fairly large, 
thick, four-sided prisms, which melt and carbonize on heating. It 
is not attacked by hydrochloric acid even at 300° or by boiling 
with a mixture of sulphuric and nitric acids. Potassium per- 
manganate only attacks it very slowly, while it is oxidized to 
carbon dioxide and acetic acid by heating with chromic acid 
solution.. On heating with sulphuric acid, it yields the same 
products as hydromellitic acid. 
Methyl rsohydromellitate, C,H,(CO,.CH,),, is formed by the 
action of methyl iodide on the silver salt, which is a fine granular 
precipitate. It crystallizes in needles, which melt at 125° and 
are insoluble in water, but dissolve readily in alcohol (Baeyer). 
The cause of the isomerism of these two acids is unknown. 


s-TRIETHYLBENZENE, (,H,(C.H,). 


2494 Jacobsen prepared this hydrocarbon by the distillation 
of a mixture of acetone and methylethylketone with sulphuric 
acid,! while Friedel and Balsohn obtained it by the action of 
ethylene on a mixture of aluminium chloride and benzene.’ It 
is a liquid, which boils at 214°—218°, and is converted by 
oxidation into trimesic acid. 


1 Ber. Deutsch. Chem. Ges. vii. 1430. 
2 Bull. Soc. Chim. xxxi. 540; xxxiv. 635. 


382 AROMATIC COMPOUNDS. 


DIPROPYLBENZENES. 


Paradipropylbenzene, C,;H,(C3H,),, has been obtained by the 
action of sodium on a mixture of paradibromobenzene and propyl 
bromide. It is a strongly refractive liquid, which smells like 
sassafras oil and boils at 218°—220°. It is oxidized by dilute 
nitric acid to parapropylbenzoic acid. 

Dibromoparadipropylbenzene, C,H. 2br,(C 3t1,)>, 18 formed by the 
action of bromine on the Reeeoinn in the cold and crystallizes 
from alcohol in lustrous needles or rectangular prisms, melting 
at 48°. 

Dinitroparadipropylbenzene, CgH(NO,),(C,H,)2, separates from 
alcohol in large, colourless, rectangular tablets, which become 
yellow in the air, and melt at 65° 

Propylisopropylbenzene, C,H,.C,H,.CH(CH,),, has been ob- 
tained by the action of zinc ethyl on cymyl chloride and is a 
liquid, which: boils at 211°—213° and is oxidized by dilute nitric 
acid to propylbenzoic acid and bromoterephthalic acid.? 

IN-isopropylbenzene, C,H,[CH(CH,).]., was prepared by Silva 
by the action of alumimium chloride on a mixture of benzene 
and propyl chloride or isopropyl chloride (p. 153), as a pleasant 
smelling liquid, which boils at 202°—206°3 


AMYLTOLUENES, CH,.C,H,.C,H,(CH,).. 


Para-amyltoluene is formed by the action of sodium on a 
mixture of parabromotoluene and amyl bromide, and isa pleasant 
smelling liquid, which boils at 213°. It is converted into tere- 
phthalic acid by chromic acid solution, mane nitric acid yields 
liquid substitution products. : 

Meta-amyltoluene is the product of the action of aluminium 
chloride on a mixture of toluene and amyl chloride or amylene. 
It is aliquid, which has an aromatic odour, somewhat resembling 
that of camphor, boils at 207°—209° and yields isophthalic acid 
on oxidation.° 


1 Korner, Ann. Chem. Pharm. ccexvi. 223. 

2 Paternd and Spica, Ber. Deutsch. Chem. Ges. x. 1746. 
3 Bull. Soc. Chim. xiii. 320. 

4 Fittig and Bigot, Ann. Chem. Pharm. cxli. 162. 

5 Essner and Gossin, Bull. Soc. Chim. xlii. 213. 


ISOHEXYLBENZENE., — 383 





ISOHEXYLBENZENE, C.H,.C,H,(CH,),. 


This substance has been obtained by acting upon a mixture 
of amyl bromide and benzyl chloride with sodium. It is a 
pleasant smelling liquid, which boils at 212°—213°, and behaves 
in a similar manner to pentylbenzene (p. 351) when heated 
with bromine.! 


ACIDS OF THE FORMULA (,H,,0.. 


2495 Cumenylpropionic acid, C,H,.C,H,.C,H,.CO,H, is formed 
when cumenylacrylic acid is heated with hydriodic acid and 
phosphorus. It crystallizes in plates, melting at 75°5°, and is 
converted by concentrated nitric acid into two orthonitro-acids, 
one of which probably contains the propyl, the other the 
isopropyl-group. 

Cumenylbromopropionie acid, C,H,.C,H,C,H,Br.CO,H, _ is 
obtained by the combination of hydrobromic acid with cumenyl- 
acrylic acid, and crystallizes from ether in lustrous prisms, 
melting at 85°—87°? 

Metamidocumenylpropionie acid, C,H,.C,H,(NH,)C,H,0,, is 
formed by the action of sodium amalgam on an _ alkaline 
solution of metamidocumenylacrylic acid and crystallizes from 
ether in long, pointed tablets, which melt at 102°—103°.8 


CH..CH, ~ 
noe ay , 1s obtained by 
heating the mixture of orthonitro-acids with zinc and hydro- 
chloric acid, but may be more easily prepared from cumeny]l- 
acrylic acid (p. 389). It is readily soluble in alcohol and 
separates from benzene on the addition of ligroin in rhombic 
tablets or prisms, which melt at 134°4 

Amylbenzoic acid, (CH;),C,H,.C,H,.CO,H. The nitril of this 
acid is formed when amylphenyl phosphate, (C,H,,.C,H,),PO,, 1s 


Propylhydrocarbostyril, C;H,.C,H 


1 Aronheim, Ann. Chem. Pharm. clxxi. 223 ; Schramm, ibid. ccxvili. 391. 
2 Perkin, Journ. Chem. Soc. 1877, ii. 660. 

3 Widman, Ber. Deutsch. Chem. Ges. xix. 418. 

4 Widman, ibid. xix. 27738. 


384 AROMATIC COMPOUNDS. 


heated with potassium cyanide, and is a liquid which has a 
characteristic aromatic odour and boils at 260°—263°. The acid 
crystallizes from hot water in small needles, which melt at 158° 
and readily sublime.! 


KETONES AND KETONIC ACIDS. 
2496 a-Durylmethylketone, (CH,),C,H.CO.CH,, is formed by 


the action of aluminium chloride on a mixture of a-tetramethyl- 
benzene and acetyl chloride. It is a strongly refractive liquid, 
which has a characteristic, not unpleasant smell and boils at 
253°—255°. It is reduced in alcoholic solution by zinc dust 
to a-durylmethylcarbinol, (CH;),C,H.CH(OH)CHs, which is a 
yellowish liquid, boiling above 300°. 

a-Durylglyoxylic acid, (CH 3),C,H.CO.CO,H, is obtained by 
careful oxidation of the ketone with potassium permanganate, 
asa light yellow, oily liquid, which forms crystalline salts and is 
reduced in alcoholic solution by sodium amalgam with forma- 
tion of a-durylhydroxyacetic acid, (CH,),.C,H.CH(OH).CO,H. 
This substance is only slightly soluble in water, readily in 
alcohol, crystallizes in short, rectangular prisms and melts at 
156°. All these compounds are converted by the further 
action of potassium permanganate into a-tetramethylbenzoic acid, 
(CH,),C,H.CO,H, which has hitherto only been obtained in 
the form of an oily liquid. 

s-Durylmethylketone crystallizes in nacreous plates, melts at 
63° and boils at 251°. On reduction it yields s-durylmethyl- 
carbinol, which forms small, white plates, melting at 72°, 

s-Durylglyoxylic acid crystallizes from alcohol in nacreous 
scales, which melt at 124°. It is converted by reduction 
with sodium amalgam and water into s-durylhydroxyacetic 
acid, which crystallizes in small, warty masses, melting at 
146°. This is converted by oxidation into s-tetramethylbenzoic 
acid, which crystallizes in silver lustrous plates and melts 
at 109° 

Methylbenzylaceto-acetre acid, CH,.CO.C(CH,)(CH,.C,H;)CO,H, 
is only known as the ethyl ether, which is obtained by the 
action of sodium ethylate and methyl iodide on benzylaceto- 


1 Kreysler, Ber. Deutsch. Chem. Ges. xviii. 1709. 
2 Claus and Foecking, bid. xx. 3097, 


ACETOPHENONE-ACETONECARBOXYLIC ACID. 385 





acetic ether, as well as by that of benzyl chloride on sodium 
methylaceto-acetic ether. It is an aromatic smelling liquid, 
which boils at 287° and is converted into methylbenzylacetic 
acid by heating with concentrated caustic potash solution.? 

Acetophenone-acetonecarboxylic acid, C,H;.CO.CH,.CH(CO.CH;) 
CO,H. The ethyl ether of this acid is formed by the action of 
benzoylmethyl bromide, C,H,;.CO.CH,Br, on sodium aceto-acetic 
ether, and is an oily liquid, which decomposes on distillation. 
Dilute caustic potash solution readily saponifies it and the free 
acid is then precipitated by the addition of dilute sulphuric acid 
to the product. It forms crystals, but is extremely unstable and 
readily decomposes into acetophenone-acetone and carbon dioxide. 
If the ether be brought into hot alcoholic caustic potash, 
dehydro-acetophenone-acetonecarboxylic acid, C,,H,,O5, is formed. 
This substance is precipitated by petroleum-ether from its 
solution in benzene in large crystals, melting at 113°—114°. It 
forms a hydroxylamine derivative and combines with phenyl- 
hydrazine. On boiling with hydrochloric acid for a short time, 
it is converted into the isomeric phenylmethylfurfurie acid, which 
crystallizes in white needles, melts at 180°—181° and readily 
sublimes. It does not combine with phenylhydrazine and is 
converted by continued boiling with acids or by heating to 240° 
—250° with water, into phenylmethylfurfuran. 

Its formation from dehydro-acetophenone-acetonecarboxylic 
acid may be explained in the following manner : 


CH,;.CO.CH.CO,H CH,.CO———CH.CO,H. 
| + H,O = | a 
C,H,.C=C C,H;.C(OH)—CH 
CH;.C—C.CO,H 
<a | + H,O. 
O.0..C— CH. 


Phenylmethylpyrrotcarboxylic acid, C,,H,,NO,. The ethyl 
ether of this acid is formed when ethyl acetophenone-acetone- 
carboxylate is treated with aqueous ammonia: 


C,H,.CO,.CH.CO.CH, CAH.) CeO CH 
| + NH, = | >NH + H,0. 
CH=-CO.0. He HC—C.C,H, 


1 Conrad and Bischoff, Ann. Chem. Pharm. eciv. 177. 
2 Paal, Ber. Deutsch. Chem. Ges. xvi. 2865 ; xvii. 913, 2756. 


386 AROMATIC COMPOUNDS. 


It crystallizes from alcohol in small tablets, which melt at 120°. 
The free acid forms long, flat, yellowish needles, which sublime 
on heating, a portion being simultaneously carbonized. 

Derivatives in which the hydrogen of the imido-group is 
replaced are obtained by the action of amines or amido-bases 
on acetophenone-acetocarboxylic ether.! 


DIBASIC ACIDS. 


2497 Orthophenylenedipropionic acid, C,H,(CH,.CH,.CO,H),. 
When ethyl chloromalonate is heated with sodium ethylate and 
orthoxylylene bromide in ethereal solution, the ethyl ether of 
orthoxylylenedichlorodimalonic acid is formed : 


yee 
ns + 2NaCCl(CO,.C,H,), = 
\OH,Br 


CH,.CCl(CO,,C,H,), | 
ene + 2NaBr. 
\OH,.CC1(CO,.C,H,), 


It forms a thick syrup, which solidifies after standing for some 
time in long crystals and is converted by the action of zinc and 
glacial acetic acid into the ether of orthoxylylenedimalonic acid, 
an oily liquid, which decomposes on boiling with alcoholic potash 
into carbon dioxide, alcohol and orthophenylenedipropionic acid : 


CH,.CH(CO,.C,H,), 
" ie + 6KOH = 
\CH,.CH(CO,,.C,H,), 
OH, CH, CO,K 
2K,CO, + 40,H,,OH + CH, ; 
CH,.CH,.CO,K 


The free acid crystallizes from hot water in microscopic needles, 
which melt at about 160°—162°? 


1 Lederer and Paal, Ber. Deutsch. Chem. Ges. xviii. 2591. 
2 Baeyer and Perkin, bid. xvii. 452; Perkin, ibid. xix. 485; Journ. Chem. 
Soc. 1888, i. 14. 


PHENYLENEDIPROPIONIC ACIDS, 387 


Metaphenylenedipropionic acid. When the reaction mentioned 
above is applied to metaxylylene bromide, the ethyl ether of 
metaxylylenedichlorodimalonie acid is obtained as a thick yellow 
liquid, which is converted by the action of zinc dust and acetic 
acid into metaxylylenedimalonic ether. This substance is also a 
liquid and yields the acid on boiling with a solution of caustic 
potash in methyl alcohol. The latter is an oily liquid and 
decomposes when heated alone, or more completely with water 
under pressure, into carbon dioxide and metaphenylenedipropionic 
acid, which crystallizes from hot water in splendid, lustrous 
tablets and melts at 146°—147°. 

Paraphenylenedipropionic acid. In order to obtain this body, 
the ethyl ether of paraxylylenedichlorodimalonic acid is prepared. 
It crystallizes from alcohol in large, six-sided tablets, which melt 
at 86°—87°, and is converted by reduction into ethyl paraxylylene- 
dimalonate, a crystalline substance, melting at 51°. The free 
acid separates out as a crystalline powder when its aqueous 
solution is evaporated and decomposes in a similar manner to 
the meta-compound when heated, paraphenylenedipropionic acid 
being formed. The latter is almost insoluble in water and 
separates from hot methyl alcohol in characteristic, knotted 
masses, which melt at 223°—224° and sublime without de- 
composition at a higher temperature.! 

Phenylhomoparaconie acid, C,,H,,0,, is formed in a similar 
manner to phenylparaconic acid by heating benzaldehyde with 
sodium pyrotartarate and acetic anhydride. It crystallizes from 
hot water in plates and separates from dilute alcohol in well- 
formed crystals, which melt at 177°. It yields two series of salts, 
like other similar lactonic acids. Those which contain two 
atoms of metal are derived from phenylhomo-itamalie acid, C,H,. 
CH(OH)CH(CO,H)CH(CH,)CO.H, which is unknown in the 
free state. When phenylhomoparaconic acid is heated above its 
melting-point, it decomposes into carbon dioxide and phenyl-@- 
butylene (p. 327).? 

In addition to this substance, the isomeric phenylisohomo- 
paraconie acid is formed, a larger quantity being obtained when 
the foregoing mixture is only heated to 100°. It also crystal- 
lizes well and behaves in a similar manner to the preceding 
compound, but melts at 124°5°3 


1 Kipping, Journ. Chem. Soc. 1888, i. 21. 
2 Fittig, Ann. Chem. Pharm. cexvi. 119. 
3 Fittig and Liebmann, Ber. Deutsch. Chem. Ges, xx. 3182. 


388 AROMATIC COMPOUNDS. 


The constitution of these acids is explained by the following 
formule : 


Phenylhomoparaconic acid. Phenylisohomoparaconic acid. 
CO,H CH,CO,H 
| V 
C.H,.CH.CH.CH.CH, C,H,.CH.C.CH, 
| | 
O——CO O——CO 


Phenylacetosuccinie acid, C,H,.CH(CO,H)CH(CO.CH,).CO,H. 
The ethyl ether is formed by the action of ethyl phenylbrom- 
acetate, C,H,.CHBr.CO,.C,H,, on sodaceto-acetic ether! It 
crystallizes from dilute alcohol in small, lustrous plates, melting 
at 75°—76°. The free acid forms fascicular groups of large plates 
and melts at 120°—121°. 

When the ether is treated in alcoholic solution with sodium 
amalgam, phenylvalerolactonecarboxylic acid is formed : 


C.H,.CH.CO.OH C.H,.CH.CO.OH 
2H 


+ 2H = = 
CO,H.CH.CO.CH, CO,H.CH.CH(OH).CH, 
C,H,.CH.CO 
Oe tO), 


| 
CO,H.CH.CH—CH, 


This crystallizes from dilute alcohol in quadratic plates, melting 
at 167°5°, and, like all lactonic acids, forms two series of salts.” 

Phihalyldi-acetie acid, C,,H,,0,. Phthalyldimalonic ether is 
always formed as a by-product in the preparation of phthalyl- 
malonic ether. It crystallizes from alcohol in lustrous prisms, 
melting at 48°5°, and yields the potassium salt of phthalyldi- 
acetic acid on boiling with caustic potash solution : 


Reade NUR re Cee) 


20-7 NERO lG- Ho, 
C,H CH,.CO,K 

co” ESCA tie Oe aCe OT eae Ge 
=0-%4 OH CG. | ; 


6KOH = 


Phthalyldi-acetic acid is readily soluble in water and crystal- 
lizes from ether in vitreous prisms, which melt at 158°? 


1 Righeimer, Ber. Deutsch. Chem. Ges. xiv. 430. 
2 Weltner, zbid. Ixvi. 18, 790. 
3 Wislicenus, Ann. Chem. Pharm. cexlii. 28. 


ALLYLISOPROPYLBENZENE, 389 


HYDROCARBONS, (,,H,, AND THEIR 
DERIVATIVES. 


2498 Allylisopropylbenzene or Isopropylphenylpropylene, (CH), 
CH.C,H,.CH—CH.CH,, is formed when cumenylcrotonic acid 
is heated. A better yield is obtained by first preparing cumenyl- 
bromobutyric acid from it by the addition of hydrobromic acid 
and then heating this with sodium carbonate solution. It is a 
liquid, which boils at 229°—230° and does not polymerize when 
heated to 160°—200° for a considerable time. Its dibromide 
crystallizes from alcohol in tablets which melt at 59° 

Phenylisohexylene, C,H;.CH—CH.CH,.CH(CH,),. When iso- 
hexylbenzene is treated with bromine vapour at 150° and the 
product distilled, this olefine is formed as the dibromide, C,H, 
CHBr.CHBr.CH,.CH(CH,),, which crystallizes from alcohol in 
small plates or needles, melting at 79°—80° (Schramm). 


ACIDS OF THE FORMULA (,,H,,0.. 


2499 Cumenylacrylicacid, (CH,),CH.C,H,CH—CH.CO,H, was 
prepared by Perkin from cuminaldehyde by heating with sodium 
acetate and acetic anhydride.? It crystallizes from alcohol in 
white needles and from benzene in obliquely pointed prisms,’ 
which melt at 157°—158". 

Orthonitrocumenylacrylie acid or Orthonitro-isopropyleinnamic 
acid, (CH,),CH.C,H,(NO,)C,H,.CO,H, is formed by the action 
of fuming nitric acid on cumenylacrylic acid. Orthonitro- 
propylecimnamic acid is simultaneously formed, the isopropyl 
being converted into the propyl group (Widman). Paranitro- 
cinnamic acid is also present among the products, the isopropyl 
group having been by a remarkable reaction replaced by the 
nitroxyl group (Einhorn and Hess). 

Nitrocumenylacrylic acid crystallizes from hot alcohol in 
hard, compact, straw-yellow prisms, which melt at 152°—158°, 
It is oxidized by chromic acid to orthonitrocumic acid. It com- 

1 Perkin, Journ. Chem. Soc. 1877, ii. 664. 


2 Ibid. 1877, i. 396 ; Einhorn and Hess, Ber. Deutsch. Chem. Ges. xvii. 2015, 
3 Widman, zbid. xix. 255, 


390 AROMATIC COMPOUNDS. 





bines with bromine to form nitrocumenyldibromopropionic acid, 
(CH,),CH.C,H,(NO,)C,H,Br,.CO,H, which crystallizes in mono- 
symmetric prisms. If it be dissolved in caustic soda solution, 
the liquid boiled for a moment and a few grains of grape sugar 
added, cumine-indigo separates out. 

Orthamidocumenylacrylic acid, (CH,),CH.C,H,(NH,)C,H,. 
CO,H, is formed when ferrous sulphate solution is added to the 
ammoniacal solution of the nitro-acid. It crystallizes from 
alcohol in flat, strongly lustrous, yellow prisms, which melt at 
165° with evolution of gas. When its hydrochloride is boiled 
with water, the following compound is formed. 

/ PHC 
Cumostyril, Ee alee | , crystallizes from 
Na OO 1) 
alcohol in long, lustrous needles, melting at 168°—169°. 

Orthohydroaycumenylacrylic acid, (CH,),CH.C,H,(OH)C,H., 
CO,H,is formed by the action of nitrous acid on the amido- 
acid and crystallizes from dilute alcohol in oblique needles, 
melting at 176°. 

Metanitrocumenylacrylie acid is formed by heating metanitro- 
cuminol with sodium acetate and acetic anhydride. It is very 
readily soluble in alcohol and crystallizes from hot benzene 
in transparent, obtuse-angled tablets, which melt at 141°. 

Metamidocumenylacrylie acid crystallizes from ether in trans- 
parent, lustrous, six-sided tablets and melts at 165°. 

Metahydroxycumenylacrylic acid crystallizes from alcohol in 
concentrically grouped flat needles or plates, melting at 
205°—206°. | 

Orthonitropropyleinnamic acid, C,H,.C,H,(NO,)C,H,.CO,H, is 
readily soluble in hot alcohol and benzene and crystallizes from 
the latter in spherical aggregates of yellowish-white needles, 
which melt at 122°—123°. It is converted into orthonitropara- 
propylbenzoic acid by oxidation. 

Orthamidopropyleinnamie acid, C,H,.C,H,(NH,)C,H,.CO,H, 
crystallizes from alcohol in yellow, lustrous needles, which melt 
at 154°—155°! If it be treated in alcoholic solution with 
sodium amalgam, propylhydrocarbostyril is formed. This sub- 
stance is also obtained in a similar manner from amidocumenyl- 
acrylic acid, the isopropyl being converted into the propyl group.” 
The same intermolecular change occurs when cumenylacrylic 
acid is converted into cumenylpropionic acid, since the acrylic 


s 1 Widman, Ber. Deutsch. Chem. Ges. xix. 273. 2 Tbid. xix. 413. 


PHTHALYLACETO-ACETIC ACID. 391 


residue, like the methyl group, favours the formation of normal 
propyl derivatives. 
CH—C.CHICH 
Isopropyleoumarin, ae , was obtained 
O CO 
by Perkin, who named it “valeric coumarin,’ by heating sodium 
salicylaldehyde with valerianic anhydride. It crystallizes 
from alcohol in large, transparent prisms, which melt at 54° and 
have a faint odour, resembling that of coumarin.” 





UNSATURATED DIBASIC ACIDS. 


2500 Phthalylaceto-acetic acid, C,,H,O0,, is only known in the 
form of the ethyl ether, which is obtained by the action of 
phthalyl chloride on sodium aceto-acetic ether : 


Cl, CH,.CO.CH, 
H, pas : ae 
& CO,.0,H, 
/=se CO.CH, 
| + 2HCl. 


HK 30 CO,,.0,H, 


It crystallizes from hot alcohol or glacial acetic acid in 
six-sided plates; when it is gradually deposited, however, it 
forms compact, obtuse-angled crystals, melting at 124°3 It 
dissolves in cold concentrated sulphuric and nitric acids and 
is reprecipitated by the addition of water. When its solution 
in sulphuric acid is heated to 65°, it decomposes into alcohol, 
acetic acid and phthalylacetic acid. Cold ammonia converts it 
into phthalyldiamide. It combines with phenylhydrazine to 
form the compound C,H,O, : C(CO,.C,H,)C(CH,)N,H.C,H,, 
which crystallizes in compact tablets and melts at 236°—238°. 

Benzaceto-acetrc-ether-orthocarboxylic acid, CH,.CO.CH(CO,,. 
C,H,)CH,.C,H,.CO,H, is formed by the action of zinc dust 
and glacial acetic acid on the ether of phthalylacetic acid. It 
crystallizes in fascicular groups of needles, melts at 92° and is 


1 Ber. Deutsch. Chem. Ges. xix. 2796. 

2 Perkin, Journ. Chem. Soc. 1868, 58. 

8 E. Fischer and Koch, Ber. Deutsch. Chem. Ges. xvi. 651 ; Biilow, Ann. Chem. 
Pharm. eexxxvi. 184. 


291 


392 AROMATIC COMPOUNDS. 





converted by boiling with baryta water into benzylacetone-ortho- 
carboxylic acid (p. 359). It combines with phenylhydrazine 
to form the compound CH,C(N,H.C,H,)CH(CO,.C,H,)CH,. 
C,H,.CO,H, which crystallizes in yellowish needles and melts at 
235° with decomposition (Biilow). 

Phenyldehydrohexonecarboxylic acid, C,,H,,0,. The ethyl 
ether is obtained by the action of trimethylene bromide and a 
solution of sodium in absolute alcohol on ethyl benzoylacetate : 


CH, Br Crome GA BAF 


+ = 
CH,.CH,Br CH,.CO,.C,H, 
CH,-0-C.C,H, 
| 4+ QHBr. 
CH,.CH,,.C.CO,.C,H, 


It crystallizes from ether. or petroleum-spirit in splendid 
monosymmetric prisms, melts at 59°—60° and boils at a higher 
temperature without decomposition. The free acid is only 
slightly soluble in water, readily in alcohol, from which it crystal- 
lizes in large, monosymmetric prisms. It melts at 142°—144° 
with evolution of carbon dioxide and decomposes completely at 
a slightly higher temperature into this and phenyldehydrohexone, 
C,,H,,O. This substance is a thick, aromatic smelling liquid, 
which boils at 249°—251° and polymerizes to a gelatinous mass 
on standing. It combines with hydrobromic acid to form 


benzoylbutyl bromide: 


C,H,.C——-O——CH, C,H;.CO 
| . +,HBr = 
CH—CH,—CH, CH. CH Che hear 


The latter crystallizes from dilute alcohol in plates resembling 
those of benzoic acid, while it separates from petroleum-ether in 
oblique, six-sided tablets. Phenyldehydrohexone is regenerated 
when it is heated with alcoholic potash. 

If the acid be boiled for some time with water, benzoylbutyl 
alcohol, C,H;.CO.C,H,.OH, is formed. It is a crystalline 
substance, which soon passes into its ether anhydride, phenyl- 
dehydrohexone.? | 

Benzal-levulinie acid, C,H,.CH—C(CH,.CO.CH,).CO,H, is 
formed when levulinic acid is heated with benzaldehyde and 


1 Perkin, Journ. Chem. Soc. 1887, i. 726 ; Ber. Deutsch. Chem. Ges. xix. 2557. 


ISOBUTENYLSTYROLENE. 393 
a a er ae ae A 


sodium acetate, and forms small, compact crystals, which melt 
at 120°—125°. It is converted by alkaline reduction into benzyl- 
hydroxypentylic acid, C.H;.CH,.CH[CH,.CH(OH).CH,|CO,H, 
which is precipitated by acids in the form of its lactone. The 
latter crystallizes from carbon disulphide in large, transparent, 
colourless prisms, melting at 85°! 


HYDROCARBONS, (©,H»—1, AND THEIR 
DERIVATIVES. 


2501 Lsobutenylstyrolene, C,H,.CH—CH.C—C(CH,),, was ob- 
tained by Perkin by heating cinnamaldehyde with isobutyric 
anhydride and sodium isobutyrate. It is a strongly refractive 
liquid, which boils at 245°—248°, has an aromatic odour and 
rapidly oxidizes in the air. A small quantity exposed to the air 
on a watch-glass becomes converted into a thick mass, resembling 
Canada balsam, within twelve hours.” 

Cinnamenylerotonie acid, C,H;.CH—CH.CH—C(CH,)CO,H, 
was prepared by Perkin from cinnamaldehyde by heating it with 
sodium propionate and propionic anhydride, It is readily soluble 
in alcohol, with difficulty in hot petroleum-spirit, from which it 
crystallizes in oblique, flat, transparent crystals, which melt at 
157°—158° and become opaque when kept for some time.* 

Phenylbutinedicarboaylic acid, C,H ;.CH—CH.CH—C(CO,H), 
is formed when cinnamaldehyde is heated with malonic acid 
and glacial acetic acid. It crystallizes in yellow needles, which 
melt at, 208° with evolution of gas and decompose completely at 
210° into carbon dioxide and cinnamenylacrylic acid (p. 369), 
while, like benzalmalonic acid, it is unaffected by boiling with 
water.* 


1 Erdmann, Ber. Deutsch. Chem. Ges. xviii. 3441. 
2 Journ. Chem. Soc. 1879, i. 141. 

3 Ibid. 1877, 406. 

4 Stuart, cbid. 1886, i. 365. 


394 AROMATIC COMPOUNDS. 





COMPOUNDS CONTAINING MORE THAN 
TWELVE ATOMS OF CARBON. 


HYDROCARBONS, C,Hop5, AND THEIR DERIVATIVES. 


2502 Trimethyldicthylbenzene, C,H(CH,).(C.H,;),, is not known 
in the free state. Its amido-compound, C,(NH,)(CH,),(C,H;)., 
is obtained by heating diethylpseudocumidine to 260°—280° 
with ethyl iodide. It is an oily liquid, boiling at 286°—290", 
and forms a hydrochloride, which is insoluble in cold, slightly 
soluble in hot water and readily in alcohol, from which it 
crystallizes in fascicular groups of needles.? 

s-Methyldipropylbenzene, C,H,(CH,)(C,H,),, was obtained by 
Jacobsen, accompanied by mesitylene and s-dimethylpropyl- 
benzene, by the distillation of acetone and methylpropylketone 
with sulphuric acid. It is a liquid, which boils at 243°—248° 
and is oxidized by nitric acid to uvitic acid.” 

Dipropylmetacresol, CH;.C,H,(OH)(C,H,.),, is formed, together 
with propylmetacresol, when metacresol is heated with propyl 
alcohol and magnesium chloride to 200°; its acetate is a liquid, 
which boils at 255°—260°. 

Di-isopropylmetacresol is obtained in a similar manner as 
a liquid, boiling at 251°. Its acetate is also a liquid and boils 
at 255°—260°.8 

Amylaylene, C,H,(CH;),C;H,,, was prepared by Fittig and 
Bigot, by the action of sodium on a mixture of amyl bromide 
and bromometaxylene. It is a pleasant smelling liquid, which 
boils at 232°—233°4 

Heptylbenzene, CgH;.C,H,,, is formed when a mixture of 
benzene and heptidene chloride, C,H,,.CHCL, is treated with 
a large quantity of aluminium chloride. The first product 
is diphenylheptane, (C,H;),CH.C,H,, which is then decomposed 
into benzene and heptylbenzene. The latter boils at 110° at a 
pressure of 10 mm. 

Tetra-ethylbenzene, C,H,(C,H;),, is obtained, together with 
hexethylbenzene, by heating ethyl bromide and benzene with 


1 Ruttan, Ber. Deutsch. Chem. Ges, xix. 2382. 

2 Ibid. viii. 1258. 

3 Mazzara, ibid. xvi. 792. 4 Ann. Chem. Pharm. cxli. 168. 
5 Krafft and Auger, Ber. Deutsch. Chem. Ges. xix. 2987. 


OCTYLBEN ZENE. 395 





aluminium chloride. It is a faintly aromatic smelling liquid, 
which boils at 251° and is oxidized by potassium permanganate 
to prehnitic acid. 

Bromotetra-ethylbenzenc, C,HBr(C,H,),, is a heavy liquid, 
boiling at 284°, 

Dibromotetra-ethylbenzene, C,Br,(C,H;),, crystallizes in colour- 
less prisms, which melt at 74°5°. 

Dinitrotetra-ethylbenzene, C,(NO,),(C,H;),, forms yellowish, 
transparent, rhombic prisms and melts at 115°. 

Tetra-ethylbenzenesulphonic acid, C,H(C,H,),SO,H, crystallizes 
in small plates or deliquescent needles and forms salts, which 
crystallize well. 

Teira-cthylbenzenesulphamide, C,H(C,H;),SO,.NH,, crystallizes 
from dilute alcohol in large, compact, monosymmetric prisms, 
which melt at 104°—105° 

Octylbenzene, C,H,.C,H,,, is formed by the action of sodium on 
a mixture of bromobenzene and octyl bromide ? or octyl chloride.® 
It is a pleasant smelling liquid, which has a sweetish, burning 
taste, boils at 262°—264° and has a sp. gr. of 0°852 at 14°. It 
solidifies at — 7° to a crystalline mass and is oxidized by chromic 
acid to benzoic acid, carbon dioxide and water. 

Chloroctylbenzene, C,5H,Cl.C,H,,, is obtained by the action of 
chlorine in presence of iodine on the hydrocarbon and is an oily 
liquid, which boils at 275°. 

Bromoctylbenzene, C,H, Br.C,H,,, boils at 290°. 

Para-vodo-octylbenzene, C,H,J.C,H,,, was obtained by Beran 
from paramido-octylbenzene by means of the diazo-reaction. 
It is a heavy, yellow oil, which has a faint aromatic odour, boils 
at 318°—320° and is oxidized by chromic acid to paranitrobenzoic 
acid. 

Ahrens has obtained an iodo-octylbenzene by treating octyl- 
benzene with iodine and mercuric oxide. It is a yellow liquid, 
solidifies at —4° becomes instantly coloured red in the lght 
and decomposes completely on heating. 

Orthonitro-octylbenzene, C,H,(NO,)C,H,,, 1s formed, together 
with its isomerides, by the action of fuming nitric acid on the 
hydrocarbon. It is a thick, yellow oil, which has an aromatic 
odour and decomposes on heating. 

Metanitro-octylbenzene crystallizes from alcohol in long, thin, 


1 Galle, Ber. Deutsch. Chem. Ges, xix. 1744. 
2 v. Schweinitz, zbid. xix. 640. 
3 Ahrens, zbid. xix. 2717. 


396 AROMATIC COMPOUNDS. 


pliant needles, which have a faint odour, melt at 123°—124° 
and sublime readily. Itis converted by potassium permanganate 
into metanitrobenzoic acid. 

Paranitro-octylbenzene is only formed in small quantity and 
can readily be separated from the meta-compound by sublima- 
tion, since it is less volatile. It is thus obtained in lustrous, 
yellowish needles, which melt at 204° and yield paranitrobenzoic 
acid on oxidation. 

Paramido-octylbenzene, C,H,0NH,)C,H,,, 1s obtained when 
octyl alcohol is heated to 270°—280° with zinc-chloride- 
aniline, and in small quantity when the alcohol is heated to 
300° with aniline hydrochloride. It is an odourless, oily liquid, 
which boils at 310°—311° and solidifies at a low temperature 
in large plates, melting at about 19°5°. It forms characteristic 
salts, which crystallize well. 

Octylbenzoie acid, C,H,,.C,H,CO,H, was first prepared by 
Beran, who heated the formyl derivative of the amido-base with 
zinc dust and converted the nitril thus obtained into the acid 
by heating with alcoholic potash. The free acid is slightly 
soluble in hot water and crystallizes from alcohol in small plates 
or. needles, melting at 139°. 

Paramido-caprylbenzene, C,H,.(CH,)CH.C,H,.N H,, is obtained 
from secondary octyl alcohol in a similar manner to amido-octyl- 
benzene and is an odourless liquid, which boils at 290°—292°, 
does not solidify at —20° and forms well-defined salts. 

It is converted by the diazo-reaction into para-todo-capryl- 
benzene, O,H,.(CH,)CH.C,H,I, a yellow, oily liquid, which boils 
at 304°—305° and is oxidized by chromic acid to paranitrobenzoic 
acid.t | 

Octyltoluenc, C,H,,.C,H,.CHs, is still unknown; its amido- 
derivative is prepared by heating octyl alcohol with zine chloride 
orthotoluidine to 280°; it is an odourless liquid, boiling at 
324°—326°? 

Di-amylbenzene, C,H,[C,H,(CH,),]., 1s formed by the action 
of aluminium chloride on a mixture of benzene and amyl 
chloride. It is an aromatic smelling liquid, which boils at about 
265°, tastes like turpentine and has a sp. gr. of 0°8868 at 0°.8 

Hexethylbenzene, C,(C,H,),, 1s obtained when a mixture of 
benzene and ethyl bromide is allowed to stand in contact 


1 Beran, Ber. Deutsch. Chem. Ges. xviii. 1381. 
2 Ibid. xviii. 145. 
3 Austin, Bull. Soc. Chim. xxxii. 12. 


PIPITZAHOIC ACID, 397 





with aluminium chloride; it crystallizes from alcohol in 
arborescent monosymmetric prisms, often three or four mches 
in length, which readily cleave parallel to the axis of length, 
melt at 126° and boil at 305° 

Cetylbenzene, C,H;.C,,H33, is the product of the action of 
sodium on a mixture of iodobenzene and cetyl iodide. It 
crystallizes well, melts at 27° and boils at 230° at a pressure 
of 15 mm. | 

Cetylphenol, C,H,(OH).C,,H,,. Fuming sulphuric acid con- 
verts cetylbenzene into the sulphonic acid. The slightly 
soluble sodium salt of this yields the phenol on fusion with 
caustic potash. It crystallizes well, has neither taste nor 
odour, melts at 77°5° and boils at a pressure of 16 mm. at 
260°—261°. 

Amidocetylbenzene, C,H,(NH,)C,,H.,. Cetylbenzene is con- 
verted by nitration into nitrocetylbenzene, C,H,(NO,)C,,Hys, 
which is a crystalline powder, melting at 35°—36°, and is 
converted by reduction into amidocetylbenzene. The latter 
crystallizes well, melts at 53° and boils at 254°—255° at a 
pressure of 14 mm. 

Octodecatylbenzcne, C,H,.C,,H,,, has been prepared from 
octodecatyl iodide in a similar manner and crystallizes from 
alcohol in small, silver lustrous plates, melting at 36°. It 
boils at 249° at a pressure of 15 mm. and solidifies in lustrous 
tablets. 

Octodecatylphenol, C,H ,(OH)C,.H,,, crystallizes from alcohol in 
large, lustrous plates, which melt at 64° 


PIPITZAHOIC ACID, C,,H,,0,. 


2503 The root known as “ Raiz del Pipitzahuac” is employed 
in Mexico as an energetic aperient, which produces no unpleasant 
after effects. In the year 1855, Professor Rio de la Loza dis- 
covered that the active substance is deposited in the root in the 
form of golden-yellow prisms, while Dr. Schaffner, of San Luis 
Potosi, sent a small specimen in the same year to Liebig, who 
intrusted Weld with the investigation. This chemist determined 
the composition of the substance and gave it the name which 


1 Galle, Ber. Deutsch. Chem. Ges. xvi. 1744. 
2 Krafft and Steinmann, ibid. xix, 2982. 


398 AROMATIC COMPOUNDS. 


is still used! In 1856, Schaffner discovered the plant, which 
belongs to the order of the Composit, and named it Trizis 
pipitzahuac. After his death his collection passed into the 
hands of his friend, Vigener, of Biebrich, who found in it a large 
amount of the root and drew attention to it again in 1884, At 
his request an investigation of pipitzahoic acid was undertaken 
by Anschiitz, who carried it out in conjunction with Leather ;? 
the subject was also studied by Mylius.* 

It was found that the substance is not a monobasic acid, as 
was supposed by Weld, but a hydroxyquinone, C,HO,(OH) 
(C,H, + ,)(C,H., —1), containing two side chains, the con- 
stitution of which is still unknown. 

Pipitzahoic acid crystallizes from dilute alcohol or Henin in 
small, golden-yellow plates and from ether in oblique, rhombic 
tablets, which melt at 102°—103°, readily sublime and volatilize 
with steam. Its alkaline solution has the colour of potassium 
permanganate, the origmal substance being thrown down by 
carbon dioxide. Reducing agents convert it into the colourless 
hydropipitzahoic acid, C,,H,.(OH),, which rapidly oxidizes in 
the air. 

Amilidopipitzahoie acid, C,,H,,0,(0H)NH.C,H,, is formed by 
the action of aniline on the solution of the acid and crystallizes 
in dark purple coloured, lustrous needles, which melt at 133° 
and are converted by heating with ammonia into amidopipitzahoic 
acid, C,,H,,O,(0OH)NH,. This substance crystallizes from alcohol 
in lustrous, brownish red needles, melts at 151° and forms a 
deep blue coloured solution in alkalis. 

Hydroxypipitzahote acid, is obtained by treating the hot 
alcoholic solution of the anilido-acid with sulphuric acid. It 
crystallizes from ether or benzene in red plates, which melt at 
138° and form a purple coloured solution in alkalis. 


ALCOHOLS OF THE FORMULA (C,H2,_,0. 


2504 The following compounds are, according to their empirical 
formule, homologous with benzyl alcohol, and are therefore 
described here although their constitution is quite unknown. 


1 Ann. Chem. Pharm. xcv. 88. 


2 Ber. Deutsch. Chem. Ges. xviii. 709 and 715; Ann. Chem. Pharm, cexxxvii. 90. 
3 Ber. Deutsch. Chem. Ges. xviii. 936. 


CYNANCHOL. | 399 





Cynanchol, C,,H,,0. Cynanchum acutum, a creeping plant, is 
looked upon in the district of the Oxus as exceedingly poisonous 
and especially harmful to camels. It contains a milky sap, which 
was investigated by Butlerow, who was unable to detect any 
polsonous principle in it. He obtained from it, however, a 
crystalline substance, to which he gave the name cynanchol. 
Hesse has subsequently shown that it is a mixture of two 
compounds, which may be separated by recrystallization from 
alcohol.” 

Cynanchin crystallizes in large, broad, lustrous plates, which 
melt at 148°—149° and are slightly soluble in cold, readily in 
hot alcohol. 

Cynanchocerin forms lancet-shaped needles, melts at 145°— 
146° and dissolves readily in hot alcohol, while it is almost 
insoluble in cold alcohol. 

Whether these compounds are really alcohols remains to be 
proved. They cannot be phenols, since they do not dissolve in 
alkalis, but may perhaps be ethers. Butlerow, to ascertain this, 
heated cynanchol with hydriodic acid and obtained a small 
amount of a volatile iodide, together with an amorphous residue, 
which was insoluble in alkalis. This result, therefore, favours 
the supposition that the substances are ethers. 

Lactucerol or Lactuceryl alcohol, C,,H,,0. The poisonous 
lettuce (Lactuca virosa), contains a juice which, after drying, 
forms the German lactucarium, which is made in Zell, on the 
Moselle, where the plants are cultivated on the slopes.* It 
contains a large amount of a crystalline substance, which is 
called lactucerin. This substance was found by Hesse to be a 
mixture of the acetic ethers of two isomeric alcohols. In order 
to prepare them, lactucarium is extracted with petroleum-ether, 
the solution evaporated and the residue exhausted with alcohol, 
which dissolves out the lactucerin. The latter is purified by 
recrystallization, saponified with alcoholic potash and the 
alcohols precipitated with water, washed and dried. 

a-Lactucerol separates out on cooling when the mixture is 
boiled with a little alcohol, and is purified by boiling with 
animal charcoal and recrystallization. It crystallizes from 
alcohol of 90 per cent. in long, silky needles, which resemble 
those of caffeine and contain one molecule of water, while it 
separates from ether or chloroform in anhydrous needles. It 


1 Ann. Chem. Pharm. ¢clxxx. 352. 2 Ibid. excii. 182. 
3 Flickiger, Pharmakognosie, 180. 4 Ann. Chem. Pharm. ccexxxiv. 243. 


400 AROMATIC COMPOUNDS. 





melts at 179° and may be volatilized in a current of carbon 
dioxide. Its solutions are dextrorotatory. 

a-Lactuceryl acetate, C,gH55-C,H,O0,, 1s obtained by heating the 
alcohol with acetic anhydride ; it crystallizes from hot alcohol in 
small plates and melts at 210°. 

8-Lactucerol does not readily crystallize from alcoholic solution, 
but separates from ether or chloroform in long, silvery needles. 
Its solutions have a feebler rotatory power than those of the 
a-compound, 

B-Lactuceryl acetate crystallizes in small plates, melting at 
230°. 

Sycoceryl alcohol, C,,H,,0. Among the products which were 
exhibited at Paris in 1855 was a resin which had been obtained 
from Ficus rubiginosa, in New South Wales, and which it was 
proposed to apply to technical purposes. It was investigated by 
Warren de la Rue and H. Miiller, who found in it, together with 
a resin and caoutchouc, a crystalline substance, which they 
proved to be the acetate of an alcohol, to which they gave the 
name sycoceryl alcohol (ctxoy, fig; «npos, wax). The resinous 
constituent is readily soluble in cold alcohol; boiling alcohol 
extracts the acetate from the residue, and it is then saponified 
by a solution of sodium in absolute alcohol. 

Sycoceryl alcohol crystallizes from hot alcohol in silky needles, 
resembling those of caffeine, which form masses resembling 
wavellite. It melts at 90° and is converted by acetyl chloride 
into the acetate. 

Sycoceryl acetate, C,,H4.C,H,O,, crystallizes from alcohol in 
small plates and from ether in six-sided tablets, which melt 
at 118°—120°. It only undergoes slight decomposition on 
distillation. 

Sycoceryl benzoate, C,.H4.C,H;O0,, is formed when the alcohol 
is heated with benzyl chloride, and crystallizes from benzene in 
prisms.t 

Cinchol or Cinchyl alcohol, C,,H,,0. It has long been known 
that Peruvian bark contains a fat or wax in addition to quinine 
and other alkaloids. This substance was first carefully investi- 
gated by Hesse, who found that it contains a series of isomeric 
alcohols. All genuine barks derived from the various species of 
cinchona contain one of these, which has been named cinchol. 
In order to extract it, the bark is exhausted with petroleum- 
spirit, the solution evaporated and the residue recrystallized 

1 Phil. Trans. 1860, 48; Jahresber. Chem. 1861, 637. 


CHINCHOL AND CUPREOL. 401 


from alcohol. The crude product is then heated with acetic 
anhydride and the acetate thus obtained purified by further 
recrystallization and finally decomposed with alcoholic potash. 

Cinchol crystallizes from alcohol in long leaflets or broad 
plates containing one molecule of water, which is lost on 
warming or on standing over sulphuric acid. It melts at 139° 
and volatilizes, apparently without decomposition, when heated 
in a current of hydrogen. | 

Cinchyl acetate, Co ,H33.C,H,0,, crystallizes from hot alcohol in 
small white needles, melting at 124°. Its solution in chloroform, 
like that of cinchol itself, is levorotatory. 

Cupreol or Cupreyl alcohol, C,,H3,0, occurs with quinine in 
Cuprea bark (Remijia pedunculata, R. Purdicana) and with 
cinchol in several true cinchona barks, and is extracted in a 
similar manner to cinchol. It crystallizes from alcohol in satin- 
lustrous plates containing one molecule of water, and from 
petroleum-spirit in long, delicate needles, which melt at 140° 
and can be volatilized in a current of hydrogen. Its solution in 
chloroform is more strongly lmvorotatory than that of cinchol. 

Cupreyl acetate crystallizes from alcohol in small plates and 
melts at 126°. 

Quebrachol or Quebrachyl alcohol, Cy,H.,0, occurs in the 
white Quebracho-bark (Aspisdosperma Quebracho), which also 
contains alkaloids and is employed in medicine in South 
America. Hesse has also detected it in some cinchona barks. 
It is obtained by extraction with petroleum-spirit and crystalliza- 
tion from alcohol. It crystallizes in small plates containing 
water, which is readily lost, melts at 125°, volatilizes without 
decomposition and has less levorotatory power than cinchol. 

Quebrachyl acetate forms small plates, which are anhydrous 
and melt at 115°? 

Llicie alcohol, C,;H,,0, was discovered by Personne in bird 
lime, which is obtained by allowing the inner portion of the 
bark of the holly (lex aguzfoliwm) to ferment. In order to 
prepare the alcohol, bird lime is dried at 100° and the residue 
extracted with chloroform and petroleum-spirit. This dissolves 
the ethereal salts of ilicyl, and these are then decomposed by 
heating with alcoholic potash. Ilicyl alcohol is scarcely soluble 
in dilute alcohol, readily in pure alcohol and forms nacreous 
crystals, which melt at 175° and volatilize at a higher tempera- 
ture, forming a vapour, which has an aromatic odour. 


1 Ann. Chem. Pharm. cexxviii. 288 ; ecxxxiv, 375. 2 Ibid. ccxi. 272. 


402 AROMATIC COMPOUNDS. 


Tlicie acetate, C,,H,,.C,H,0, forms crystals, which melt at 
204°—206° 

Mochyl alcohol, C,,H,,0, occurs as an ether of palmitic acid 
in tori-mochi or Japanese bird-lime, which is prepared from 
Mochi-no-ki (Ilex integra). .It resembles ilicyl alcohol, melts at 
234° and decomposes at a higher temperature with formation of 
mochylene, C,,H,,, which is a thick oil. In company with this 
substance occurs ilicic alcohol, C,,H,g0, which melts at 172°. 
Both of these alcohols are converted by heating with palmitic 
alcohol into a substance which is identical with purified 
bird-lime.? 


HYDROCARBONS OF THE FORMULA (C,H,, .. 

2505 Lsopropylbutenylbenzene or Isopropylphenylbutylene (CH,), 
CH.C,H,.CH—CH.CH,.CH,;, was obtained by Perkin by com- 
bining cumenylangelic acid, prepared from cuminaldehyde, 
butyric anhydride and sodium acetate, with hydrobromic acid, 
and heatmg the product with sodium carbonate solution. It is 
a liquid, which boils at 242°—243°, has a sp. gr. of 0°8875 at 
15° and has an odour, which resembles that of cuminaldehyde 
to a certain extent, but is fainter and more fruit-like. 

Lsopropylphenylbutenyl bromide, C,,H,.Br,, crystallizes from 
alcohol in transparent tablets and melts at 77°23 

B-Lsopropylbutenylbenzene or [sopropylphenylisobutylene (CH), 
CH.C,H,.CH—C(CH,),, has been prepared by Perkin, who 
heated a mixture of isobutyric anhydride, cuminaldehyde and 
sodium isobutyrate. It boils at 234°—235°, has a sp. gr. of 
0889 at 15° and forms a liquid dibromide.‘ 


ALCOHOLS OF THE FORMULA (C,H,,_.0. 


2506 These bodies, according to their empirical formulz, are 
isomeric with cinnamy] alcohol; their constitution is still quite 
unknown. 

Cholesterin or Cholesteryl alcohol, CygH4,.0H. In the year 
1788, Green drew attention to a characteristic fatty substance, 

1 J. and J. Personne, Bull. Soc. Chim. xiii. 150. 


2 Divers and Kawakita, Journ. Chem. Soc. 1888, i. 268. 
3 Ibid. 1877, ii. 665. 4 [has SOs. Al. 


CHOLESTERIN. 403 





which occurred in gall-stones. This body was classified by 
Fourcroy with spermaceti and adipocire (Pt. I. p. 677), 
but Chevreul pointed out the different nature of these bodies 
and named the substance in question cholesterin (cholestérine, de 
yon et otepeds, bile solide)... Jt also occurs in the gall, brain, 
nerves, spleen, blood, milk and excrements, as well as in certain 
morbid products of the animal economy, in cod liver oil and other 
animal fats, and in fish, eggs, &c. It has also been discovered in 
Peru guano, and occurs in wool fat, partially in the free state and 
partially in the form of ethers. Berthelot has prepared several 
of its ethers and thus proved that it is an alcohol? It is best 
obtained from gall-stones, which frequently consist almost entirely 
of it, by extracting the powder with boiling water and crystal- 
lizing the residue from alcohol. It may also be exhausted with 
benzene, the solution evaporated and the residue purified by 
recrystallization.® 

If gall-stones are not obtainable, it may be extracted from the 
gall, which must be evaporated to a thin syrup and extracted 
with ether. Brains contain about 0°4 per cent. of cholesterin 
and 80 per cent. of water. If they be mixed with enough 
plaster of Paris to absorb all the water and the hard mass powdered 
and extracted with ether, the cholesterin and a small quantity 
of fat enter into solution. The liquid is then cooled to 0°, at 
which temperature the fat separates out, the filtered solution 
evaporated and the residue freed from adhering fat by boiling 
with alcoholic potash; it is then finally purified by recrystalliza- 
tion from alcohol.* Cholesterin crystallizes from chloroform in 
needles, which melt at 145°—146°, and from alcohol or ether in 
small plates or monosymmetric tablets, containing one molecule 
of water, which is lost over sulphuric acid or at 100°. It is 
insoluble in water, and is scarcely soluble in cold alcohol, but 
dissolves in hot alcohol, ether and chloroform. Its solutions 
are levorotatory. It boils under diminished pressure above 
360° (Chevreul), but may also be volatilized at the ordinary 
pressure, if it be carefully heated. It combines with bromine 
to form a dibromide, C,,H,,Br,0, which crystallizes in thin 
needles.° 


1 Recherches sur les Corps gras etc. In the original, which contains a large 
number of printer’s errors, the word is printed ceped, instead of orepeds. 

2 Salkowski, Zeitschr. anal. Chem, xxvi. 557. 

3 Thudichum, Fresenius’ Zettschr. i. 122. 

4 Walitzky, Beilstein’s Handb. ii. 678. 

5 Wislicenus and Moldenhauer, Ann. Chem. Pharm. exlvi. 178. 


404 AROMATIC COMPOUNDS. 








Cholesterin gives several characteristic reactions. If it be 
brought into contact with sulphuric acid and a little iodine, a 
violet colouration is produced, which changes to blue, green and 
finally red. If its solution in chloroform be shaken with an 
equal volume of sulphuric acid of sp. gr. 1°76, the solution 
becomes coloured purple-red and the acid shows a green fluores- 
cence. Ifa few drops of the chloroform solution be now poured 
into a basin, the colour changes into blue, green and finally 
yellow.t. When cholesterin is evaporated with nitric acid, a 
yellow residue is left, which is coloured red when ammonia is 
added to it before it has cooled. The colour is not changed by 
caustic potash solution, so that cholesterin can in this way be 
distinguished from uric acid.? 

In order to detect cholesterin, the suspected substance is 
heated with benzoic acid, the characteristic benzoate, which is 
described below, being formed.? 

Cholesteryl chloride, C,,H,,Cl, is formed by the action of 
hydrochloric acid or phosphorous pentachloride on cholesterin 
and crystallizes from hot alcohol in long needles, which melt at 
97° and show a violet fluorescence.° 

If it be heated with a solution of sodium in absolute alcohol, 
cholesterylene, C,,H,,, 18 formed. ‘This body is only slightly 
soluble in alcohol, readily in ether and crystallizes in long 
transparent needles, melting at 80°. 

When the chloride is boiled with alcohol and sodium 
amalgam, hydrocholesterylene, C,,H,,, 1s obtained. It forms 
feathery crystals, melting at 90°.® 

Cholesteryl acetate, C,.Hy.C,H,0,, is obtained by heating 
cholesterin with acetic acid, acetyl chloride or acetic anhydride 
(Rayman). It crystallizes from alcohol in small needles, melting 
at 113°. 

Cholesteryl butyrate, Cj.H,,.C,H,O,, was obtained by Berthelot 
by heating cholesterin with butyric acid to 200°; it is a readily 
fusible mass, 

Cholesteryl stearate, O,,H,.C,,H3,0,, crystallizes in small 
needles, melting at 65°. 


1 Hesse, Ann. Chem. Pharm. ccxi. 283 ; Salkowski, Fresenius’ Zeitschr. xi. 443. 
2 Schiff, ibid. exv. 313. 
3 Schulze, Fresenius’ Zeitschr. xvii. 174. 
4 Berthelot, Ann. Chim. Phys. [8] lvi. 54 ; Lobisch, Ber. Deutsch. Chem. Ges. 
v. 510. 
> Rayman, Bull. Soc. Chim. xlvii. 898. 
6 Walitzky, Beilstein’s Handb. ii. 129 and 131. 


ISOCHOLESTERIN. 405 





Cholesteryl benzoate, C,,.H,,.C,H,O,, is scarcely soluble in 
boiling alcohol and crystallizes from ether in characteristic, 
rectangular tablets (Fig. 4), which melt at 150°—151°. 





Fie. 4. 


Cholesterylamine, Cy,H,3.NH,, is formed when the chloride is 
heated with alcoholic ammonia and crystallizes in small iridescent 
plates, which melt at 104° and then show a characteristic, bluish 
violet fluorescence, resembling that of the precious opal; this 
phenomenon is also shown by the fused chloride (Loebisch),. 

Dinitrocholesterin, Cy,H,,(NO,),0, is obtained by the action 
of fuming nitric acid on cholesterin and crystallizes from hot 
alcohol in fine needles, melting at 120°—121°1 

2507 Isocholesterin, C,,H,,0, occurs, together with choles- 
terin, in wool fat. The latter may be removed by extraction 
with alcohol, while its ethers and those of isocholesterin remain 
behind. The mixture is then saponified with alcoholic potash 
at 100° in closed vessels, the solution evaporated and the residue 
extracted with ether. Two isomeric alcohols are thus obtained 
in the ethereal solution, which is evaporated and the residue 
‘heated to 200° with four parts of benzoic acid. The benzoates 
thus obtained crystallize from ether in characteristic forms, 
which may be separated mechanically by washing and are then 
saponified. 

Tsocholesterin separates from a dilute alcoholic solution in 
plates, while its concentrated solution solidifies to a jelly. It 
crystallizes from ether or acetone in fine, transparent needles, 
melting at 137°—138°. It is dextrorotatory and gives the 
cholesterin reaction with chloroform.’ 

Its chloride and acetate are resinous; the stearate forms fine 
- needles, melting at 72°. 

‘Isocholesteryl benzoate crystallizes from ether im microscopic 
needles and from acetone in fascicular aggregates of lustrous 
needles, melting at 190°—191°. 


1 Preis and Raymann, Ber. Deutsch. Chem. Ges, xii. 224. 
2 Schulze, Jowrn. Prakt. Chem. [2] vii. 163 ; xxv. 458. 


406 AROMATIC COMPOUNDS. 


Phytosterin or Phytosteryl alcohol, C,,H,,0, was discovered by 
Benecke in leguminous fruits, almonds and other seeds, and 
was considered by him to be cholesterin,’ until Hesse, who 
prepared it from Calabar beans, proved its individuality and 
gave it the name now in use? (guTov, plant). It is widely 
disseminated in the vegetable kingdom, and occurs in wheat, 
maize, cotton seed and probably all seeds, as well as in the fatty 
oils derived from them, in many fungi and in the sugar beet,? &c. 
It is best obtained from seed peas, which are extracted with 
petroleum spirit, the solution evaporated and the residue freed 
from an oily impurity by exposure on filter paper and then 
recrystallized from alcohol (Hesse). 

It thus forms plates, containmg one molecule of water, while 
it crystallizes from ether or chloroform in anhydrous needles 
melting at 132°—133°. It has a less rotatory power than choles- 
terin, but gives the same reaction with chloroform.4 While 
cod-liver oil and other animal fats contain cholesterin alone, 
plytosterin always occurs in the oils derived from seeds, but is 
not contained in palm oil and only in small quantity in olive oil. 
An adulteration of cod-liver oil with seed oil can therefore be 
detected by isolating the cholesterin of the mixture. This sub- 
stance when pure crystallizes from alcohol in characteristic 
tablets, melting at 146°, whilst the melting-point is lowered by 
the presence of phytosterin, and the needle-shaped crystals of 
the latter can readily be observed among those of choles- 
terin. Since olive oil only contains a very small quantity of 
phytosterin, while cotton-seed oil contains it in relatively large 
amount, an adulteration of the former with the latter may 
probably be recognized without much difficulty. 

Phytosteryl acetate, C,,H4.C,H,O,, crystallizes from hot alcohol 
in lustrous satiny plates, melting at 120°.° 

Paracholesterin, Cy,H,,O, isa constituent of Acthaliwm septicum, 
a fungus which grows on old tan heaps. It crystallizes from 
alcohol in plates, containing one molecule of water, and from 
ether or chloroform in silky needles, melting at 134°—135°5°.' 
It has a feebler levorotation than phytosterin and gives the 
chloroform reaction (Schulze). 


Ann. Chem. Pharm, exxii. 249. 

Ibid, cxcii. 175. 

Lippmann, Ber. Deutsch. Chem. Ges. xx. 3201. 
Hesse, Ann. Chem. Pharm. ccxi. 283. 
Salkowski, Fresenius’ Zeitschr. xxvi. 557. 
Hesse, Ann. Chem. Pharm. ecxxvill. 296. 

7 Reinke and Rodewald, 7zbzd. cevil. 229. 


an Pr wh eH 


DAUCOSTERIN. 407 


Paracholesteryl benzoate, C,,H,3.C,H,O,, crystallizes from ether 
in thin, lustrous, rectangular plates, which melt at 127°—128*. 

Caulosterin, C,,H,,0, occurs in the root and stem (caulvs, 
xavnros) of seedlings of the yellow lupine, which have been 
allowed to grow in the dark. It is also levorotatory and gives © 
the chloroform reaction; it crystallizes from alcohol in lustrous 
plates, containing a molecule of water of crystallization which is 
lost at 100°, and melts at 158°—159°. Its benzoate crystallizes 
from ether in thin lustrous plates. 

Daucosterin, C,,H,,0. A red colouring matter, which is 
known as carotin, occurs in the carrot (Daucus carota), together 
with a colourless body, termed hydrocarotin by Husemann in 
the belief that it only differed from carotin in containing a 
larger amount of hydrogen.? According to Arnaud, it is 
identical with phytosterin, but this view has been disputed by 
Reinitzer, who showed that it is a new cholesterin, for which he 
retained the name hydrocarotin.? The carrot contains about 0°01 
per cent. of this substance, which crystallizes from acetone in 
long needles and from methyl alcohol in large, nacreous plates, 
containing water of crystallization, which is soon lost. It melts 
at 137°, is levorotatory and gives the chloroform reaction. Its 
acetate forms scales, melting at 127°5°, while the benzoate 
crystallizes in tablets, which resemble those of cholesteryl 
benzoate and melt at 145°4 


1 Schulze and Barbieri, Journ. Prakt. Chem. [2] xxv. 159. 
2 Ann. Chem. Pharm. cxvii. 200. 

3 Compt, Rend. cii. 1319. 

4 Reinitzer, Monatsh. Chem. vii. 597. 


292 


408 AROMATIC COMPOUNDS. 


GROUP OF THE TERPENES AND CAMPHORS. 


2508 The pines, firs, and other coniferous plants are rich in 
resins and volatile hydrocarbons. The resinous juice issuing from 
the bark of many of these trees or obtained from them by means 
of incisions, which is called turpentine and was known to the 
ancients, is a mixture of these. Dioscorides relates that the 
resin oil (7vacéXavov) was extracted from this resin by boiling it 
with water in a vessel over which wool was suspended, which was 
allowed to become saturated with the vapours and then wrung 
out into another vessel. The same method is described by 
Pliny: HL pice fit, quod prssinwm appellant, quum coquitur, 
velleribus supra halitum ejus expansis, atque ita expressis; ... . 
color oleo fulvus. 

As the process of distillation was gradually improved, oil of 
turpentine was more frequently prepared and, like spirits of 
wine, received the name aqua ardens. 

Marcus Graecus, who lived in the eighth century, or accord- 
ing to some authors at a later period, gives the following 
directions : Recipe terebinthinam, et destilla per alambicum aquam 
ardentem, quam umpones in vino cur applicatur candela et ardebit 
upsa. Libavius treats of it in an appendix to his chapter on 
alcohol, and it was rarely at that early period described as an 
oil, this word being however used by Arnoldus Villanovanus in 
the thirteenth century and in the fifteenth century by Johann 
von St. Amando, a physician of Tournay, who says: Olewm de 
terebinthina fit siemiliter per sublimationem, et est clarum ut 
aqua fonts, et ardet ut ignis graecus. 

Libavius generally speaks of it as spiritus terebinthinae, and 
Lemery as esprit de therebentine, but the latter chemist re- 
marked in 1700 that this spirit is really wne hutle actherée. 

Other volatile oils became known in the thirteenth century. 
Raymond Lully says that such are obtained by the distillation of 


| a a 


TERPENES AND CAMPHORS. 409 


many plants with water and speaks more particularly, im common 
with Arnoldus Villanovanus, of oil of rosemary. A very large 
number of ethereal oils was then prepared by the adherents of 
Paracelsus in their endeavours to extract the quintessence from 
plants. 

It was long believed that the characteristic odour of these 
oils did not arise from the oils themselves but from a substance 
mixed with them. This odorous body, which was thought to be 
extremely subtle and scarcely ponderable, was named spiritus 
rector by Boerhave in the year 1732. Macquer in 1778 expressed 
the opinion that it was a true gas, and Fourcroy in 1794 devoted 
an entire chapter of his Hlemens d’ Histoire naturelle et de Chimee 
to the discussion of this ardme; four years later, however, he 
sought to prove that the odour was that of the oils themselves 
and was not due to an admixed substance. 

The investigation of these oils showed that many of them, as 
oil of turpentine, oil of lemons, &c., have the formula C,,H,,, 
and that isomeric hydrocarbons, frequently accompanied by 
other compounds, occur in other ethereal oils. These yield 
isomeric or polymeric hydrocarbons when submitted to the 
action of heat or sulphuric acid. It was further observed that 
oil of turpentine combines with hydrochloric acid to form a 
crystalline compound, C,,H,,.HCl, an isomeric liquid being 
simultaneously formed, while oil of lemons yields the solid body, 
C,,H,,.(CIH),. Oil of turpentine also combines with water 
under certain conditions to form the crystallized hydrate C,,H,, 
+ 2H,0, which was also obtained from other ethereal oils. 

Berthelot, who made a detailed investigation of oil of turpen- 
tine and its derivatives, came to the following conclusions : 

Oil of turpentine exists in two optically isomeric modifica- 
tions, the lvorotatory terebentene and the dextrorotatory 
australene (p. 415). Both of these yield the isomeric hydro- 
chlorides mentioned above, while a dihydrochloride is formed by 
the continued action of concentrated hydrochloric acid, which 
appears to be identical with that derived from oil of lemons. In 
addition to these, an unstable, liquid compound of the formula 
C,,H,6(C1H), + 2(C,,H,,-HCl) exists. Careful elimination of the 
hydrochloric acid from the solid monohydrochlorides yields the 
isomeric crystalline hydrocarbons terecamphene and austracam- 

1 Dumas, Ann. Chem. Pharm. vi. 245; Blanchet and Sell, bid. vi. 259 ; 
Blanchet, zbid. vii. 154; Souberan and Capitaine, ibid. xxxiv. 311; Deville, 


ibid. xxxvii. 176 ; xxi. 349 ; Wiggers, ibid. xxxiii. 358 ; lvii. 247 ; see also ibid, 
li. 390. 


410 AROMATIC COMPOUNDS. 


phene, which are also optically different, while an inactive 
camphene (p. 417) is formed under other conditions. These 
hydrocarbons form hydrochlorides from which they can be 
isolated unaltered. Oil of turpentine is converted by heating 
into tsoterebene or austraterebene, which, like oil of lemons, com- 
bines with two molecules of hydrochloric acid and occupies an 
intermediate position between oil of turpentine and oil of 
lemons. 

Berthelot then gives the following résumé : 

“The hydrocarbon, C,,H,,, in certain of the forms in which 
it occurs in nature, as for example in terebentene, is the starting 
point for two series of compounds: (1) The monatomic camphol 
series (including the monohydrochloride or camphhol hydro- 
chloric ether C,,H,,Cl, the camphenes, C,,H,,, and the camphol 
alcohols, C,,H,,O). (2) The diatomic terpil series (including the 
dihydrochlorides, the hydrates, C,,H,,O,, and the terpilenes). 

“Hach of these series forms a chief group, which is divided 
into secondary series (australene, terebentene, &c.), the isomeric 
members of which correspond in pairs. Each of these series 
has an inactive hydrocarbon as type, that of the first group 
being camphene and of the second group terpilene.” ! 

In addition to this, oil of turpentine is converted by the 
action of sulphuric or phosphoric acid into the inactive terebene, 
which combines with hydrochloric acid to form a semi-hydro- 
chloride (C,,H,,),HClL. 

As it had been found that the isomeric hydrocarbons, C,,H,g, 
are closely related to camphor, they had been termed cam- 
phenes, but as this name was subsequently adopted by Berthelot 
for a single definite substance, it was changed to terpenes.? The 
close relations existing between these substances and cymene 
were not discovered till a later period. It was believed that 
an extremely large number of terpenes existed, which differed 
from each other in physical properties, such as optical behaviour, 
smell, boiling-point, &c., and that numerous chemical isomerides 
existed in addition to these physical isomerides, 

Light was first thrown upon this little-understood group by 
the researches of Tilden. This chemist, in conjunction with 
Shenstone, found that the substances in question can be divided 
into. two classes; the members of the first of which boil at 
about 160°, while the boiling-points of the second class approach 


1 Ann. Chem. Pharm. lxxxiv. 350 ; ex. 367 ; Suppl. ii. 226, 
2 Kekulé, Lehrd. ii. 464. 


= ee 


— 


ee ee ee eee ae eee 


TERPENES AND CAMPHORS. 411 





174°. Both combine with nitrosyl chloride to form compounds 
C,)H,,NOCI, which exhibit characteristic differences.1 He sub- 
sequently showed that those of the first class, to which oil of 
turpentine belongs, form a solid monohydrochloride with hydro- 
chloric acid and that the liquid product simultaneously formed 
is a mixture of cymene with monohydrochloride and a dihydro- 
chloride. The latter is readily formed by the action of 
hydrochloric acid on the higher boiling terpenes, such as: 


Citrene from oil of lemons, 
Hesperidene from oil of oranges, 
Bergamene from oil of bergamot, 
Carvene from cumin oil, 

Terpene from pine-needle oil, 
Terpene from resin spirit. 


Sylvestrene, a substance which occurs in Swedish and Russian 
oil of turpentine, also forms a characteristic dihydrochloride.? 
Riban had previously found that the terebene, which is formed 
by the action of concentrated sulphuric acid on oil of turpen- 
tine, is a mixture of cymene with a terpene, which he looked 
upon as pure terebene.. Armstrong and Tilden, however, 
showed that the latter contains camphene and another terpene, 
for which they retained the name of terpilene ;* it is also formed 
when terpene dihydrochloride is heated with water and when 
the hydrate is treated in a similar manner with dilute sulphuric 
acid. 

A complete explanation of this subject was first given by 
Wallach’s detailed investigation. According to this chemist, 
there are eight chemically different terpenes, which fall into 
three classes : 


Pinene Limonene Terpinene 
Camphene Dipentene Phellandrene 
| Sylvestrene 
Terpinolene 


Pinene, which exists in two optically isomeric forms, occurs in 
oil of turpentine and other ethereal oils. It forms a mono- 
hydrochloride, which is converted by elimination of hydrochloric 

1 Journ. Chem. Soc. xxxi. 554. 


2 Ber. Deutsch. Chem. Ges. xii. 1133. 
3 Ibid. xii, 1752. 


412 AROMATIC COMPOUNDS. 


acid intocamphene. The latter combines with one molecule of 
hydrochloric acid and may be reobtained unaltered from this 
compound. 

The terpenes of the second group are characterized by the 
formation of crystalline tetrabromides, C,,H,,Br, by means of 
which they can be readily detected. Pinene and limonene are 
converted by being strongly heated into dipentene, which forms 
the same dihydrochloride as is formed by the action of concen- 
trated hydrochloric acid on pinene and of hydrochloric acid gas 
on hmonene. The latter terpene occurs in several ethereal oils, 
while sylvestrene is a product of the dry distillation of pine- 
wood and is a very stable compound. Terpinolene and terpinene 
are constituents of terpilene and of the products of the further 
decomposition of dipentene. This substance, as also terpinene 
and phellandrene, is found in nature. The two latter are dis- 
tinguished by the formation of crystallized compounds of the 
formula C,,H,,N,O., with nitrogen trioxide. 

The smell of the pure terpenes resembles that of oil of lemons 
or oranges in a greater or less degree. 


THE PINENE GROUP. 


2509 Ou of turpentine has been long prepared by the dis- 
tillation of turpentine with water, that derived from Pinus 
maritima being employed for this purpose in South-west France. 
The French oil of turpentine consists almost entirely of lavo- 
pinene or terebentene, which also occurs in Strassburg turpentine 
(Pinus picea), in Venetian turpentine (Pinus larix) and in 
Canada balsam (Pinus balsamea). English oil of turpentine, so 
called because it comes to the European markets from England, 
is prepared in the United States, especially in North Carolina, 
from the turpentine of Pinus australis. It is simply distilled 
from copper retorts without the addition of water and the oil 
received in the casks in which it is exported? It contains 
dextropinene or australene, which also occurs, together with 
sylvestrene, in Swedish and Russian oil of turpentine. The 
latter product differs from those already described in not being 


1 Fliickiger and Hanbury, Pharmacographia, 2nd Edit. 605. 


.THE PINENE GROUP. _ . 413 





obtained from turpentine but.from pine-wood tar (Pinus sylvestris 
and Pinus Ledebourit). 

Another product, named templinol or oil of fir-cones, is 
prepared in Switzerland from the cones of the silver fir (Pinus 
picea). It consists of levopinene and has a very pleasant 
smell, resembling that of orange flowers, while the freshly 
prepared oil from the turpentine of the same tree has a smell 
resembling that of lemons.’ 

Commercial oil of turpentine contains oxidation products and 
has a characteristic, unpleasant smell ; when heated to 250°—270", 
it is partially polymerized and partially converted into the 
isomeric dipentene. If its vapour be passed through a tube 
heated to just below redness, isoprene, C,H,, heptine, C,Hy,, 
toluene, metaxylene, cymene, terpilene (dipentene) and _ poly- 
terpenes are formed,? while the products at a red heat are 
benzene, toluene, metaxylene and its isomerides, naphthalene, 
phenanthrene, anthracene and methylanthracene, all of which 
occur in coal-tar.* 

Chlorine acts so energetically on oil of turpentine as to cause 
ignition, so that when paper soaked in the oil is brought into 
chlorine gas, finely divided carbon separates out and hydrochloric 
acid is formed. Substitution products are formed by a more 
moderate action, or addition may take place, bromine acting 
in similar manner. When iodine is added to oil of turpentine, it 
dissolves and the mass then detonates, hydriodic acid being 
evolved ; if it be very gradually added and the mixture heated, 
cymene is formed. 

Oil cf turpentine absorbs oxygen very readily, carbon dioxide, 
formic acid, acetic acid, &c., being formed and the whole being 
finally converted into a resinous mass. According to Schonbein, 
ozone is also formed in this gradual oxidation and combines with 
the oil of turpentine to form a characteristic, strongly oxidizing 
compound, while Kinzett states that the peroxide, C,,H,,O,, is 
formed and that this decomposes on heating with water into 
hydrogen peroxide and camphorie acid.’ 


CyoH,,0, + 2H,0 = C,H,,0, + H,0,. 
The ignition of oil of turpentine by the addition of fuming 


3} Fliickiger, Jahresb. Chem. 1855, 642. 

2 Blanchet and Sell, Ann. Chem. Pharm. vi. 262. 

3 Tilden, Journ. Chem. Soc. xlv. 411. 

4 Schultz, Ber. Deutsch. Chem. Ges. x. 118. 

5 Journ. Chem, Soc. xvii. 511 ; xviii. 210 ; xix, 243, 


414 AROMATIC COMPOUNDS. 





nitric acid was known in the seventeenth century, as was also 
the fact that other oils behave in a similar manner. Geoffroy 
in 1726 stated that the experiment succeeds most completely 
when a mixture of nitric and sulphuric acids is employed, and 
this was confirmed by Rouelli in 1747. 

A series of products has been obtained by the action of dilute 
nitric acid on oil of turpentine, the constitutions of some of 
which have only been recently ascertained. Acetic, propionic, 
paratoluic and terephthalic acids are formed, together with tere- 
binic acid, C,H,,O,, and dimethylfumaric anhydride,’ C,H,O.. 
The latter compounds have the following constitutional formule: 


Terebinic acid. Dimethylfumaric anhydride. 


GH CCH <a H CH,C.CO. 
0 
| 1 ary 2 

i ke OH,.0.CO 


Chromic acid solution converts oil of turpentine into acetic 
acid, terebinic acid and terpenylic acid, C,H,,O,, the constitution 
of the last of which is still unknown, a small quantity of 
phthalic acid being also formed.” 

A current of boron fluoride converts oil of turpentine into a 
polymeride, which is a viscid, fluorescent liquid and boils at 
300° (Berthelot). 

Since oil of turpentine readily dissolves resins, it is employed 
for the manufacture of lacs and varnishes and as a diluent of oil- 
colours. It is a strong antiseptic and is employed in medicine, 
its vapour being inhaled, for example, in cases of bronchitis, 
while the old oxidized oil serves as an antidote against phos- 
phorus poisoning. When taken inwardly, it imparts the odour 
of violets to the urine, a fact which was known to the Romans; 
the same effect is produced when the body is exposed to its 
vapours for a considerable time. 

2510 Terebentene or Levopinene, C,,H,,, was obtained by 
Berthelot by neutralizing French oil of turpentine with sodium 
carbonate and distilling under diminished pressure. It also 
occurs in oil of thyme and in oil of anise (Briihl), boils at 156° 


and has a sp. gr. of 0°8767 at 0°. 


1 Mielck, Ann. Chem. Pharm. clxxx. 45; Bredt, ibid. ceviii. 58 ; Roser, Ber. 
Deutsch, Chem. Ges. xv. 293, 1318 and 2381; Otto and Beckurts, tbid. xviii. 
825; Frost, Ann. Chem. Pharm. CCXXV1. 368 ; ; Erdmann, ibid. ccxxvili. 176. 

2 Fittig and Krafft, 2btd. ceviii. 74. 

3 Riban, Ann. Chim. Phys. vi. [5] 14. 


TEREBENTENE. 415 


Australene or Dextropinene has the same properties, but is 
dextrorotatory. It occurs in oil of turpentine, and also in those 
of wormwood and mint (Mentha viridis). 

Nitropinene, C,,H,,.NO,. Nitrous acid acts upon terebentene 
with formation of a green oil, which has not been prepared in a 
state of purity. It is converted by the action of ammonia into 
nitropinene, a yellow oil, which decomposes on heating. 

Amidopinene, C,,H,;.NH,, is formed by the reduction of nitro- 
pinene and is a light, colourless liquid, which boils at 197°—200°, 
and is converted by methyl iodide into pinyltrimethylammonium 
iodide, O,,H,,N(CH,),[, which crystallizes in nacreous plates. 

Pinene dichloride, C,)H,.Cl,, is obtained when chlorine is 
passed into oil of turpentine at — 15°, and is a liquid, which 
decomposes on heating into hydrochloric acid and cymene, 
products which are also formed, together with a diterpene 
C,H, When it is heated to 100° with zine dust.? 

Pinene dibromide, C,,H,,Br,, is formed when bromine is added 
through a capillary tube to well-cooled oil of turpentine, and 
is a liquid which is converted into cymene by heating with 
anilin.. 

Pinene nitrosochloride, C,,H,,NOCI, is obtained by passing 
nitrosyl chloride into a mixture of English or French oil 
of turpentine with chloroform, the liquid being cooled by a 
freezing mixture of salt and ice. It is a snow-white, crystalline 
powder, which is converted by alcoholic caustic soda into %so- 
nitrosopinene or pinoxime, C,,H,,(N.OH). This substance crystal- 
lizes from hot alcohol in transparent, monoclinic prisms, melts 
at 129°, readily sublimes and is only slightly soluble in water, 
but readily in hot caustic soda solution.4 

Its ethereal solution yields with sodium ethylate a precipitate 
of C,,H,,(NONa), which is converted by heating with methyl 
iodide into the methyl ether, C,,H,,(NOCH,), a liquid which 
smells like carrots.° 

Pinene hydrochloride or Pinyl chloride, C,,H,,Cl, was dis- 
covered by Kindt in 1803 and described as artificial camphor ® 

This hydrochloride of oil of turpentine or terpene monohydro- 
chloride, as it was subsequently called, is obtained by passing 


1 Pesci and Bettelli, Gaz. Chim. Ital. xvi. 337. 

2 Naudin, Bull. Soc. Chim. xxxvii. 111. 

3 Oppenheim, Ber. Deutsch. Chem. Ges. v. 628. 

4 Tilden, Jowrn. Chem. Soc. xxvii. 514; Maskelyne, tdid. xxvii. 518 ; Tilden 
and Shenstone, zbid. xxxi. 554. 

5 Goldschmidt and Ziirrer, Ber. Deutsch. Chem. Ges. xviii. 2223. 

§ Trommsdorff’s Journ. Pharm. xi, 2, 132. 


416 AROMATIC COMPOUNDS. 


hydrochloric acid into cooled oil of turpentine’ diluted with 
carbon disulphide* or benzene ;? according to Wallach, these 
diluents are superfluous, it bemg only necessary to avoid the 
presence of any trace of water and to prevent the temperature 
rising, as otherwise a certain amount of dipentene dihydro- 
chloride is obtained and forms with the pinyl chloride a mixture, 
which has a very low freezing point. 

Pinyl chloride is a crystalline mass, which appears and smells 
like camphor ; it is deposited from alcoholic solution in feathery 
crystals, which possess the unpleasant property of welding to a 
viscous mass, which adheres firmly to all objects with which it 
comes into contact. It melts at 125°, boils at 210°, does not 
combine with dry hydrochloric acid or bromine and is not 
decomposed by silver nitrate in the cold. 

Pinyl bromide, C,,H,,Br, was obtained by Deville by the 
action of hydrobromic acid on oil of turpentine. It melts at 
90°, resembles the chloride and boils with decomposition at a 
slightly higher temperature than this (Wallach). 

2511 Pinenes also occur in the following ethereal oils, their 
presence being proved by converting the fraction which boils at 
about 160° into dipentene by heating or by preparing the tetra- 
bromide from this (Wallach) or by preparing the nitrosochloride 
(Tilden and Shenstone). 

Fir-wool oil is obtained in the preparation of fir wool, by 
boiling the needles of Pinus sylvestris with water and condensing 
the vapour. It has a pleasant odour of lavender,® and contains 
a pinene besides a large amount of limonene (Wallach). It 
finds application in medicine. 

Oil of juniper is prepared both from the ripe and unripe 
berries ; the latter has an odour resembling those of juniper and 
pine needles simultaneously. It is employed in medicine, and 
forms a constituent of gin (Geniévre.) The pinene, which can 
be isolated by fractional distillation, amounts to about one-third 
of the whole and is feebly levorotatory. 

Oil of sage, extracted from the leaves of Salvia officinalis, 
contains salviol, C,,H,,O, ordinary camphor and a_pinene, 
which has all the properties of terebentene.® 


1 Oppermann, Pogg. Ann. xxii. 89. 

2 Berthelot, Ann. Chim. Phys. [8] xl. 5. 

3 Tilden, Ber. Deutsch. Chem. Ges. xii. 1131. 

4 Ann. Chem. Pharm. ccxxxix. 4. 5 Ann. Chim. Phys. \xxv. 45, 54. 

§ Muir, Journ. Chem. Soc. xxxvii. 678; Muir and Sigiura, ibid. xxxiii. 292 ; 
Tilden and Shenstone, Joc. cit. 


THE CAMPHENE GROUP. 417 


Oil of rosemary. Rosemary (ros marinus) is mentioned even 
by Pliny and was well known to the Spanish-Arabian physicians, 
being highly prized throughout the Middle Ages. Charlemagne 
recommended the cultivation of this plant, which is indigenous 
to the coasts of the Mediterranean, and occurs in Africa as far 
inland as the Sahara, whence the dried plants are transported 
by caravans into Central Africa. The ethereal oil was distilled 
from it by Raymond Lully, and its extraction is fully described 
by Arnaldus Villanovanus in his tract De Vinis. 

Oil of rosemary is manufactured in the south of France, 
Italy and Dalmatia. It is employed in pharmacy and _per- 
fumery and contains a pinene, accompanied by camphor, borneol, 
and cineol.} 

Oil of Eucalyptus is obtained from the fresh leaves of Huca- 
lyptus globulus and other species of eucalyptus. It has a 
characteristic aromatic odour and a burning, spicy taste pro- 
ducing a cooling after-effect. It is a strong antiseptic and is 
on this account employed in medicine. It contains one pinene, 
a terpene, which boils at 172°—175°, cymene,” and cineol. 

Oil of mace is obtained from mace, the arillus or husk- like 
envelope of nutmeg, and like the ethereal oil extracted from the 
nutmeg itself, consists chiefly of a dextropinene. 


CAMPHENE GROUP. 


2512 Camphene or Bornylene, C,,H,,, exists in three optically 
isomeric but chemically identical modifications. Berthelot ob- 
tained the levorotatory terecamphene by heating pinyl chloride 
or pinyl bromide, prepared from terebentene, with dry soap or 
potassium stearate to 200°—220°, while australene yielded the 
dextrorotatory austracamphene. An inactive canvphene, however, 
was the chief product when sodium benzoate was substituted 
for the stearate.° 

Riban found that terecamphene may be readily prepared by 
heating the hydrochloric acid compound of terebentene for some 
time to 180° with alcoholic potash, and that inactive camphene is 
formed when the same substance is heated to 170° with potassium 


1 Weber, Ann. Chem. Pharm. ccexxxviii. 90. 
2 Faust and Homeyer, Ber. Deutsch. Chem. Ges, vii. 63 and 1429, 
3 Ann. Chem. Pharm. Suppl. ii. 226. 


418 AROMATIC COMPOUNDS. 


acetate or sodium acetate. He also obtained Borneo-camphene by 
the action of alcoholic potash on bornyl chloride, a substance 
which will be subsequently described. This compound may be 
more readily prepared by heating the chloride for twenty hours 
to 90°—95° with a large quantity of water and a little mag- 
nesia.?_ It is also formed by the action of sodium on an ethereal 


solution of the so-called camphor chloride (p. 429).  Accord-— 


ing to Riban, it is inactive, whilst Kachler states that it is 
dextrorotatory ; if it be purified by conversion into the hydro- 
chloric acid compound and again separated, it is found to 
possess a very faint dextrorotation (Kachler and Spitzer). 
Bouchardat and Lafont, who prepared camphene by heating the 
pinyl chloride, which is prepared from French oil of turpentine, 
with alcohol and potassium acetate, found that the rotation 
varies with the temperature employed and the duration of the 
preparation,* obviously because the levorotatory modification 
is partially converted into the dextrorotatory ; inactive cam- 
phene must therefore also be formed. 

The oils of myrtle and rosemary probably contain a camphene 
in addition to pinene (Brihl). 

In order to prepare camphene, bornyl chloride is warmed with 
an equal weight of aniline and the mixture then heated to the 
boiling-point of the latter. The reaction, accompanied by 
separation of aniline hydrochloride, occurs suddenly and is 
complete after a few minutes. The mass is then allowed to 
cool, treated with hydrochloric acid and the camphene distilled 
off with steam.’ 

It may also be readily obtained by heating equal parts of 
pinyl chloride and anhydrous sodium acetate to 200° for three or 
four hours with twice the weight of glacial acetic acid, or by 
simply heating a mixture of pinyl bromide and glacial acetic 
acid for some time in a flask connected with an inverted con- 
denser.® 

Camphene is also formed, accompanied by other products, by 
the action of concentrated sulphuric acid on oil of turpentine 
(p. 422) (Armstrong and Tilden).’ 


It forms a crystalline mass, resembling paraffin, which has, 


1 Ann. Chim, Phys. [5] vi. 3538. 

2 Kachler, Ann. Chem. Pharm. exevii. 86. 

3 Kachler and Spitzer, 7bid. ec. 840; Montgolfier, Ann. Chim. Phys. [5] xiv. 
: 4 Bull. Soc. Chim. xlvii. 488. 

5 Wallach, Ann. Chem. Pharm. cexxx. 233. 6 Tbid. ccxxxix. 6, 

7 Ber. Deutsch. Chem. Ges. xii. 1752. 


é 


BORNYL ALCOHOL. 419 


according to Riban, a characteristic stale smell, while according 
to other authorities its odour resembles those of turpentine 
and camphor. It separates from alcoholic solution in feathery 
crystals, melts at 51°—52°, boils at 160° and readily combines 
with hydrochloric acid to form bornyl chloride. 

Monobromocamphene, C,,H,;Br, is formed when bromine is 
allowed to drop into a solution of camphene in a mixture of ether 
and alcohol. It is an oily liquid, which boils between 230°—240° 
with slight decomposition (Wallach). | 

2513 Bornyl alcohol, C,,H,,O0H. The history of this com- 
pound, which is usually termed Borneo-camphor or borneol, will 
be treated in connection with that of camphor. It occurs in the 
pith cavities of Dryobalanops camphora, a magnificent tree grow- 
ing in Borneo, Sumatra and Labua, and is also found in 
D. longifolia and D. Becarwi. In order to obtain borneol, the 
trees are felled and split and the camphor picked out. It is 
used to some extent on the spot as incense, especially in the ob- 
servation of funeral rites, and is exported to China, Japan and 
other districts of Eastern Asia for similar purposes. On account of 
the small quantity which is obtained—a tree yields from 1°5 to 6°5 
kilos., and sometimes does not contain any—and the high price 
—£3 10s. to £7 per kilo., according to the quality—it does not 
find a market in Europe. 

It can however be readily prepared from ordinary camphor. 
Berthelot obtained Borneo-camphor, together with campholic 
acid, by treating camphor with alcoholic potash: 


2C,,H,,0 + KOH = C,H,,0 + C,,H,,0,K- 





He therefore assumed that camphor is the aldehyde corresponding 
to borneol or camphyl alcohol. 

Baubigny then found, that when sodium isadded to a solution 
of camphor in coal-tar naphtha, sodium borneol and sodium 
camphor are formed : 


2C,,H,,0 + 2Na = C,,H,,ONa + C,,H,,ONa. 


Carbon dioxide acts upon this mixture at 100° with formation 
of the sodium salts of camphorcarboxylic acid, C,,H,,O.CO,H, 
and of borneolcarboxylic - acid, C,,H,,O.CO,H, the latter of 
which is decomposed by water into sodium bicarbonate and 
borneol.? 


1 Ann. Chem. Pharm. exii. 356. 
2 Compt. Rend. Ixiii, 221; Kachler, Ann. Chem. Pharm. excvii. 99. 


420 AROMATIC COMPOUNDS. 





Borneol however is most easily obtained by heating an alcoholic 
solution of camphor with sodium,! the followimg method being 
employed : 

“Fifty grammes of camphor are dissolved in 500 cb. cms. 
of alcohol of 96 per cent. in a capacious flask, fitted with a wide 
reversed condenser, through which 60 grms. of sodium are gradually 
added in small pieces. The operation must last for about an 
hour and the rise of temperature not be prevented by cooling ; it is, 
in fact, advisable to accelerate the completion of the reaction by 
finally adding about 50 grms. of water, the mixture being well 
agitated during this process.” 

The product is then poured into 3—4 litres of cold water, the 
separated borneol collected on a filter cloth, well washed and 
crystallized from petroleum-ether after drying.? 

Borneol is a constitutent of the ethereal oil of the Virginian 
snake-root (Aristolochia serpentaria).* It is very slightly soluble 
in water, readily in alcohol and ether and possesses an odour 
which resembles that of camphor and of pepper, or, according to 
other authorities, of patchouli. It separates from petroleum- 
ether in splendidly formed crystals, which usually have a 
tabular habit. It melts at 206°—207°*t and boils at 212°, but 
volatilizes very rapidly below its melting-point and sublimes in 
six-sided plates, while it is less volatile than camphor at the 
ordinary temperature. It is converted into camphor by the 
action of dilute nitric acid. 

Both these substances are optically active and dextrorotatory, 
while Ngai camphor consists of levorotatory borneol.® This sub- 
stance, which comes into the market in the form of white 
grains, 1s obtained in Canton and the Island Hainan from 
Blumea balsamifera, one of the tall herbaceous Composite, and 
is employed in medicine and as an ingredient of Indian ink. A 
less pure variety, which is called Bang Phien, forms crystalline 
masses, saturated with a greenish oil, and has a still more 
powerful odour than Ngai camphor. 

Levoborneol also occurs in the ethereal oil of Matricaria 
parthenium,® in oil of lavender, oil of spike, oil of rosemary, 


1 Jackson and Menke, Ber. Deutsch. Chem. Ges. xvi. 2930 ; Jackson, ibid. xvill. 
Ref. 335 ; Immendorff, bid. xvii. 1036. 

2 Wallach, Ann. Chem. Pharm. ccexxx. 225. 

3 Spica, Gaz. Chim. Ital. xvii. 318. 

4 Wallach, Ann. Chem. Pharm. ccxxxix. 226. 

5 Plowman, Jahresb. Chem. 1874, 537. 

6 Dessaignes and Chautard, Ann. Chem. Pharm. lxviii. 342; Haller, Compt. 
Rend, cili. 64; civ. 109. 


BORNEOL. 421 


and madder fusel oil ;1 it is formed in small quantity, together 
with dextroborneol, by the action of sodium on camphor.” 

Its levorotation is exactly equal in amount to the dextrorotation 
of ordinary borneol, and it yields levorotatory camphor on oxi- 
dation. When succinic acid is distilled with caustic potash, a 
faintly dextrorotatory borneol is formed in small quantity.’ 
According to Haller, this is a mixture of both the active forms, 
while an inactive borneol,* probably consisting of equal amounts 
of both modifications, is obtained by the distillation of crude 
colophene, a product of the action of sulphuric acid on oil of 
turpentine. 

If borneol be dissolved in cold petroleum-ether and treated with 
bromine, borneol bromide, C,,H,,Br,0, separates out in yellowish- 
red plates or needles, which soon decompose with formation of 
bornyl bromide and other products. Borneol also combines with 
hydrobromic acid to form the compound (C,,H,,.O),HBr, which 
is a crystalline powder, as is also the corresponding hydriodic 
acid derivative. Both of these substances are decomposed by 
water with separation of borneol. Wallach was unable to prepare 
any compound with hydrochloric acid. 

According to earlier statements, borneol is converted by heat- 
ing with phosphorus pentoxide into borneéne, C,)H,,, a liquid 
boiling at 176°—180°. Wallach has found that this substance 
does not exist, since the product, which is also obtained by the 
action of phosphorus pentoxide on camphene, is a complicated 
mixture, probably containing cymene. Pure camphene is formed 
when borneol is heated with acid potassium sulphate. 

2514 Sodium bornylate, C,,H,,ONa, is formed when borneol 
is dissolved in light coal-tar oil and heated with sodium. On 
the evaporation of the solution it separates in six-sided plates, 
which dry to a loose mass. It is soluble in water but is rapidly 
decomposed with separation of borneol. When dry carbon 
dioxide is passed into its solution in coal-tar naphtha heated to 
130° and the temperature then allowed to fall to 100°, sodium 
borneolcarboxylate, C,,H,,0.CO,Na, separates out as a crys- 
talline mass, which is soluble in cold water. If the solution 
be allowed to stand for some time, borneol crystallizes out in 
lustrous plates and sodium bicarbonate is formed.° 

1 Jeanjean, Ann. Chem. Pharm. ci. 95. 
2 Montgolfier, Ann. Chim. Phys. [5] xiv. 21, 
3 Berthelot and Buignet, Ann. Chem. Pharm. exiv. 244. 


4 Armstrong and Tilden, Ber. Deutsch. Chem. Ges. xii, 1755. 
5 Kachler and Spitzer, Monatsh. Chem, li. 228. 


499 AROMATIC COMPOUNDS. 


Methyl bornyl ether, C,\)H,,OCH,, was obtained by Baubigny 
by the action of methyl iodide or sodium bornylate, as a liquid 
boiling at 194°5°.1 

Hithyl bornyl ether, C,,H,,OC,H,, is formed in a similar manner, 
and also, together with camphene, when pinyl chloride (from 
terebentene) is treated with alcohol and sodium acetate (p. 417). 
It boils at 205°—208°, is dextrorotatory and decomposes on 
heating with concentrated hydrochloric acid into ethyl chloride 
and bornyl chloride. 

Dibornyl ether or Bornyl oxide, (C,,H,,),0, is, according to 
Bruylants, a constitutent of oil of valerian (see below), and is a 
thick liquid, which boils at 285°—290° and is unaltered by fusion 
with caustic potash. 

Bornyl chloride, C,)H,,Cl, is formed by heating borneol with 
fuming hydrochloric acid to 100°,? and by the action of phosphorus 
pentachloride upon it,’ low boiling petroleum-ether being in this 
case used as a diluent to prevent the formation of oily 
by-products. Bornyl chloride is also formed when hydro- 
chloric acid is passed into a solution of camphene in absolute 
alcohol or ether.® It is a mass, which appears like camphor, 
melts at 157° and dissolves readily in ether and petroleum- 
spirit, less readily in alcohol, from which it separates in thread- 
like crystals. It differs from pinyl chloride in its much greater 
instability. : 

Bornyl bromide, C,,H,,Br, was prepared by Kachler by heating 
borneol with fuming hydrobromic acid to 100°; it resembles the 
chloride, but melts at 74°—75°. 

Bornylsuiphurie acid, C,,H,,S0,H. Among the products 
formed by the action of sulphuric acid on French, oil of turpen- 
tine is pinyl sulphate, (C,)H,,),SO,, which is converted by 
heating with alcoholic potash into potassium bornylsulphate, 
C,,H,,SO,K. This salt crystallizes in fine plates and is not 
readily soluble in cold water.® 

Bornyl carbonate, (Cy,H,,),CO;, is formed, together with the 
carbamate, by the action of cyanogen on sodium bornylate and 
treatment of the product with water. It crystallizes in six- 
sided tablets or plates, which melt at 215° and are dextrorota- 


1 Bull. Soc. Chim. [2] x. 110 and 210. 

2 Berthelot, Ann. Chem. Pharm. cxii. 366. 3 Kachler, ibid. exevii. 92. 

4 Wallach, zb¢d. ecxxx. 231. 

> Riban, Ann. Chim. Phys. [5] vi. 863; Kachler and Spitzer, Ann. Chem. 
Pharm. cc. 345. 

§ Bouchardat and Lafont, Compt. Rend. cv. 1177. 


BORNYL ACETATE. 423 


tory. Ngai camphor is even more easily converted into a 
leevorotatory carbonate, which also melts at 215°. 

Bornyl carbamate, C,,H,,0.CO.NH,, crystallizes in monosym- 
metric prisms, which show positive hemihedral faces and melt at 
115°, while the substance derived from levoborneol is negatively 
hemihedral and melts at 126°-—127° 

Bornyl acetate, C,,H,;.0.C,H,0, is formed when borneol is 
heated to 150° with acetic anhydride,* and by the action 
of silver acetate on the chloride* or of acetyl chloride on 
borneol.t It is a thick, pleasant-smelling liquid, which boils at 
227° and crystallizes on standing for some time in masses, which 
melt at 24.° 

According to Bruylants, this ether also occurs in oil of 
valerian (Valeriana officinalis) and boils at 235°—240°. Gerhardt 
succeeded in proving the presence in it of a terpene, valerianic 
acid and borneol, the last being only found in old samples or 
after treatment with caustic potash.® Bruylants has now detected, 
in addition to these, dibornyl ether, the acetate and the two 
following substances :° 


Melting-point. 
’ Bornyl formate, C,,H,,.0O.CHO . . ... 225°—280° 


Borny! valerate, C,,H,,.0.C;H,O .. . 255°—260° 


Haller states that the borneol separated from these ethers is 
identical with Ngai camphor.’ 

By the continued heating of the so-called terebene (p. 410) 
with glacial acetic acid, Bouchardat and Lafont obtained a 
bornyl acetate, which smells like thyme, boils at 215° and yields 
an inactive borneol on saponification.® 

2515 a-Bornylamine, C,)H,;.NH,, is formed when camphor, 
which is the ketone corresponding to borneol, is heated for some 
hours to 220°—240° with twice its weight of ammonium formate, 
a-bornylformamide being the first product : 


C,,H,,0 + 2NH,.CHO, =C,,H,,.NH.CHO +(NH,)HCO,+H,0 


This substance is converted by boiling with hydrochloric acid 
into a-bornylamine hydrochloride, from which the base may be 
set free by caustic potash. It is also obtained by the action of 


1 Haller, Compt. Rend. xcii. 1511; xciv. 869; xcvili. 578. 
2 Montgolfier, dnn. Chim. Phys. [5] xiv. 5. 


3 Kachler and Spitzer, loc, cit. * Schrotter, Monatsh. Chem. ii. 224. 
5 Ann, Chem. Pharm. xlv. 34. 6 Ber. Deutsch. Chem. Ges. xi. 452. 
7 Compt. Rend. ciii. 151. 8 Ibid, cii. 171. 


293 


424 AROMATIC COMPOUNDS. 


sodium on an alcoholic solution of camphoroxime. On evapor- 
ation of its ethereal solution, the a-bornylamine is left as a 
brittle mass resembling camphor and possessing an odour which 
resembles those of camphor and piperidine. It melts at 158°— 
160° and boils at 199°—200°, but volatilizes tolerably quickly 
even at the ordinary temperature. 

It is levorotatory, almost insoluble in water, to which it 
imparts an alkaline reaction, and rapidly absorbs carbon dioxide 
from the air. 

a-Bornylamine hydrochloride,C,,H,,.NH,Cl,forms small needles, 
which are readily soluble in water and alcohol, but insoluble in 
ether. It combines with platinum chloride and mercuric 
chloride to form double salts, which, like the other salts of 
bornylamine, crystallize well. 

a-Bornylformamide, C,,H,,,NH(CHO), is also obtained by 
heating the base with formic acid; it crystallizes from water in 
lustrous plates, melting at 61°. 

a-Bornylacetamide, C,)H,,.NH(C,H,0), separates from dilute 
alcohol in small plates, melting at 141°. 

a-Bornylearbamide, C,)H,,.NH.CO.NH,, is formed when the 
chloride is boiled with a solution of potassium cyanate; it 
crystallizes on cooling in needles, which melt at 164.° 

Other near derivatives of bornylamine have also been pre- 
pared. Bornylamine is a primary amine and gives a very well 
marked carbamine reaction with chloroform and alcoholic potash.? 

B-Bornylamvine or camphylamine, C,,H,,,.NH,, is obtained by 
the action of sodium on an alcoholic solution of camphoroxime 
anhydride, C,,)H,,N (p. 430), and is an ammoniacal smelling 
liquid, which boils at 194°—196° and is readily converted into a 
solid mass by absorption of carbon dioxide. 

8-Bornylamine hydrochloride,C,,H,,.N HCl, is readily soluble in 
water and crystallizes in thin rhombic plates. The other salts 
and double salts also crystallize well. 

B-Bornylbenzamide,C,,H,,.N H(CO.C,H,), crystallizes in prisms, 
melting at 75°—77°” 

Similarly to the a-compound, camphylamine behaves in every 
respect asa primary amine. The isomerism of the two substances 
will be subsequently explained. 

2516 Camphor, C,,H,,0. This compound, which is sometimes 
termed Chinese camphor and Japanese camphor, or Laurel 


1 Leuckart and Bach, Ber. Deutsch. Chem. Ges. xx. 104. 
2 Goldschmidt and Schulhof, ibid. xviii. 3297 ; xix. 708. 


CAMPHOR. 425 


camphor, was unknown to the Greeks and Romans. It is first men- 
tioned in the sixth century by Arabian writers and by Aétios of 
Amida in Mesopotamia, according to whom Caphura? is a rare 
and valuable medicine. It is again mentioned, together with musk, 
amber and sandal wood, among the treasures taken in the year 636 
by the Kalif Omar at the plundering of the Sassanides palace in 
Madain on the Tigris, and is subsequently noticed as a costly 
gift often presented by Indian princes to high Chinese officials. 
This camphor came from the land known as Kaisur, the present 
Sumatra, and was doubtless Borneo-camphor. The fact that 
camphor is also obtained from China is first mentioned by 
Avicenna; it was brought into Europe by the Arabians, and St. 
Hildegard in the twelfth century terms it Ganphora. Marco 
Polo was acquainted with both kinds of camphor; he states 
that the camphor from Kaisur is the most valuable, being sold 
for its weight in gold, adding that the Chinese variety is obtained 
in the south-eastern districts of the country from the camphor 
tree. Garcia de Orta, in 1653, reports that only the Chinese 
camphor is sent to Europe, that from Borneo and Sumatra being 
a hundred times more valuable, and Kimpfer, who lived in 
Japan between the years 1690 and 1692, drew special attention 
to the difference between the two varieties. In spite of these 
statements, its vegetable origin was long discredited. Agricola 
classes it with earth-resin and petroleum, “for from such materials 
camphor is probably obtained by sublimation; the supposition 
entertained by some that it is a vegetable resin or gum, is con- 
tradicted by the fact that heat is employed in its preparation, 
for noble constituents are not extracted in this way from the 
vegetable but rather from the mineral kingdom.” 

The camphor tree (Laurus camvphora L., Cinnamonum camphora, 
Nees et Ebermaier) is distributed throughout the eastern 
provinces of Central China, on the island of Hainan and very 
extensively in Formosa. It also occurs as a forest tree on the 
islands Kiushiu and Shikoku of South Japan, its growth being 
much more vigorous there than in the more northern districts. 

The camphor is frequently found collected in rifts in the stem 
of the tree and is accompanied by an ethereal oil, rich in 
dipentene (Wallach), which holds it in solution. It also contains 
levopinene and camphorogenol, C,,H,.0,, a tolerably heavy oil, 
which smells somewhat lke camphor, but more agreeably, boils 


1 The word camphor or camphora is derived from the Arabic Kafir, and this 
probably from the Sanscrit Kapiira—white. 


426 AROMATIC COMPOUNDS. 


at 212°—213°, and is partially polymerized on continued heating 
and partially converted into camphor, which is also formed by 
its oxidation.t 

The camphor which is prepared on the continent of China is 
not exported to Europe. This market is however supplied from 
Formosa, where a very rude method of extraction is in vogue. 
The trees are felled, cut up into small pieces and these spread on 
a perforated board, which is cemented with clay over a wooden 
trough, prepared from the stem of the camphor tree and caulked 
with clay. Wateris heated to boiling in this trough and the steam 
passing through the branches and pieces of wood carries off the 
camphor, which is condensed in a tolerably pure state, but with 
great loss, in pots inverted on the board. No less than 816,587 
kilos. of crude camphor were exported from Formosa in the 
year 1878. 

Japan produces about the same quantity. It used to be 
extracted, according to Kiimpfer, by boiling the wood with 
water in an iron kettle and condensing the vapour in an earthen- 
ware dome, closed at the top with rice straw. An earthenware 
retort is now employed in which the wood is boiled with water ; 
it is fitted with a wooden dome from which the vapours are led 
through a bamboo tube to the cooling apparatus. This consists 
of a wooden box containing seven transverse compartments, and 
is enclosed by a second box through which water is allowed to 
flow. The vapours are conducted through all the compartments 
in succession by means of holes placed alternately at either end 
of the dividing walls. 

The crude camphor is usually refined in Europe by mixing it 
with lime, charcoal, or iron filings and subliming the mixture in 
large glass vessels,” cakes weighing 4—6 kilos. being thus obtained. 

A more recent process now adopted in England and America 
is to sublime it from iron retorts into a cooled chamber, in the 
same way as flowers of sulphur, the crystalline sublimate being 
afterwards pressed by hydraulic power into solid disks. 

Camphor also occurs, together with borneol, in oil of spike 
(Lavandula spica), oil of lavender (Lavandula vera),* oil of 


* Yoshida, Journ. Chem. Soc. 1885, i. 779. Borneo camphor is also accom- 
panied by an oil, which appears to be a mixture of two terpenes. It resembles 
oil of camphor, but does not smell of sassafras as this does. (Fliickiger and 
Hanbury, Pharmacographia, 517.) 

2 These are called ‘‘ Bombolas,” an expression which points to a Venetian origin. 

3 Fliickiger, Pharmacognosie, 137. 


* Dumas, Ann. Chem. Pharm. vi. 248 ; Lallemand, ibid. xiv. 197 ; Bruylants, 
Journ. Chem. Soc. xxxvi. 725 ; xxxviii. 50. 


CAMPHOR. 427 


rosemary (p. 417), and oil of sage (Salvia officinalis).+ It is 

obtained artificially by the oxidation of borneol? or cymene ® 
with nitric acid, and by the treatment of camphene with platinum 
black * or chromic acid solution.? 

2517 Camphor forms a tough crystalline mass of characteristic 
taste and odour, and can only be powdered when it is moistened 
with alcohol or some other solvent. It dissolves in 1,300 parts 
of water at 20°, and at 12° in 0°8 parts of alcohol of sp. gr. 0°806. 
It is readily soluble in ether, acetone, chloroform, benzene and 
other hydrocarbons, as also in glacial acetic acid and in carbon di- 
sulphide. It melts at 175°, and boils at 204°, but volatilizes very 
rapidly at the ordinary temperature and sublimes when kept in 
closed vessels in lustrous, hexagonal crystals which frequently 
form splendid stars. This volatility probably also explains the 
fact that a small piece thrown upon water rotates rapidly until 
it has completely dissolved. This does not occur if the water be 
covered with a film of fat, &c., so that crude camphor often does 
not show the phenomenon. On the other hand it rotates when 
thrown on mercury and when it is placed on a small piece of 
wood floating on water.® 

The solutions of camphor are dextrorotatory ; the correspond- 
ing levorotatory modification is formed by the oxidation of 
lzevocamphene, while the inactive camphene yields an inactive 
camphor.’ Lzvoborneol, on the other hand, is converted into 
ordinary camphor by oxidation.® 

When camphor is heated with phosphorus pentoxide, it is 
resolved into cymene and water (p. 27), a decomposition which 
is also brought about by heating with concentrated hydrochloric 
acid to 170°. If zine chloride be employed, however, benzene, 
toluene, xylene, pseudocumene, and laurene, C,,H,, (p. 346), are 
formed in addition.1° The same products, with the exception 
of laurene, are formed when camphor is heated with zinc dust. 
Iodine acts upon it, when the mixture is heated, with evolution 
of hydriodic acid and formation of cymene, carvacrol (p. 295), 


1 Muir, Journ. Chem. Soc. xxxvii. 685. 

2 Pelouze, Ann. Chem. Pharin. xl. 328. 

3 Oppenheim, Ber. Deutsch. Chem. Ges. v. 631. 

4 Berthelot, Ann. Chem. Pharm. cx. 367. 

5 Riban, Bull. Soc. Chim. xxiv. 19. 

6 Tomlinson, Chem. News, lii. 50. 

7 Armstrong and Tilden, Ber. Deutsch. Chem, Ges, xiii. 1756. 
8 Montgolfier, Ann. Chim. Phys. [5] xiv. 29. 

9 Alexejew, Beilstein’s Handb. 1763. 

10 Fittig, Kobrich and Jilke, Ann. Chem. Pharm. exlv. 29. 
11 Schrotter, Ber. Deutsch. Chem. Gres. xiii. 1621. 


428 AROMATIC COMPOUNDS. 


laurene and other bodies, the exact nature of which has not yet 
been ascertained.t If a somewhat higher temperature, about 
250°, be employed in this reaction, inflammable gases are 
evolved in considerable amount and the hydrocarbons mentioned 
above, accompanied by others, are formed.2 The action of other 
reagents upon camphor will be subsequently mentioned. It is 
frequently employed in Eastern Asia as incense, while it finds 
application with us as a medicine, used both externally and 
internally. Like other analogous compounds it has a strong 
antiseptic action and also serves to prevent the ravages of 
clothes-moths and other insects, and for this reason it is largely 
used in natural history museums. 

Administered to a dog, it appears in the urine as campho- 
glucuronie acid, C,,H,,O,, and uramidocamphoglucuronie acid, 
the composition of which has not yet been determined. The 
former of these on boiling with dilute hydrochloric acid yields 
camphorol, C,,H,,O,, which crystallizes in thin tablets, melts 
at 197°—198*, readily sublimes and is converted by oxidation 
into camphoric acid.’ 

The constitutions of camphene, borneol and camphor may be 
expressed by the following formule : + 


Camphene. Borneol. Camphor. 
CH, OH, CH, 
| | | 
C C C 
H,0~| SCH... HLC7|SCHOH FLO 
| | | | | | 
H. Isle) cal H, H.C. | (CH 
so Nea Na 


| | | 
C,H, C,H, C,H, 


Camphene combines with hydrochloric acid to form bornyl 
chloride and borneol is converted by oxidation into camphor, 
which is the ketone corresponding to this alcohol. Further 
proofs of the accuracy of those formule will be subsequently 
adduced. Pinene, in a similar manner, combines with hydro- 
chloric acid to form pinyl chloride and this is converted by elimina- 
tion of hydrochloric acid intocamphene. The following constitu- 


1 Armstrong and Gaskell, Ber. Deutsch. Chem. Ges. xi, 151. 
? Preis and Raymann, zd. xiii. 346. 

3 Schmiedeberg and Meyer, Hoppe-Seyler’s Zeitschr. iii, 422. 
4 Wallach, Ann. Chem. Pharm. ccxxx. 269. 


CAMPHENE. 429 


tion must therefore probably be assigned to pinene and its 
hydrochloride :1 | 


CH, CH, 
é CCl 
Hc’ ‘oH HOY NOH, 


INI ee 
sak Sega Nae 
CH. 


| ie 
C,H, C,H, 


Camphene is thus formed from pinyl chloride by elimination 
of hydrochloric acid and rearrangement of the double linking. 
The fact that pinene and camphene only contain one ethylene 
linking is also confirmed by their specific refractions.” 

2518 Camphidene dichloride, C,,H,,Cl,. This compound, which 
is usually called camphor dichloride, is formed, according to 
Gerhardt, by the action of phosphorus pentachloride on camphor. 
Pfaundler then found that the compound, C,,H,,Cl,* is thus 
formed if the mixture be heated and that cymene passes over when 
the distillation is slowly conducted. Spitzer, on the other hand, 
observed that several higher chlorinated compounds are formed 
when the mixture is heated, but the dichloride can readily be 
obtained pure by avoiding any rise of temperature ;° it is also 
formed by the treatment of bornyl chloride with chlorine,® a 
reaction which corresponds to the formation of ethidene chloride 
from ethyl chloride. 

Camphidene dichloride crystallizes from alcohol in fine needles, 
while it separates from ether in large rhombic crystals. It 
melts at 155°, readily loses hydrochloric acid in the moist state, 
and is converted by the action of alkyl iodides and sodium into 
homologues of camphene. In the formation of these substances, 
hydrochloric acid and chlorocamphene are first produced and 
substitution then takes place. The following have been prepared 
by Spitzer : 

Boiling-point. 
Ethyleamphene, C,,H,,.C,H,. . . . 198°—200° 
Isobutyleamphene, C,,H,,.C,H, . . . 228°—229° 
1 Wallach, Ann. Chem. Pharm. ccxxxix. 49. 
2 Briihl, Ber. Deutsch. Chem. Ges. xxi. 145. 
3 Ann. Chem. Pharm. cxv. 29. 
4 Luginin and Lippmann, ibid. Suppl. v. 260. 


5 Ibid. exevi. 262 ; Monatsh. Chem. i. 319. 
6 Kachler and Spitzer, Ann. Chem. Pharm. cc. 240. 


430 AROMATIC COMPOUNDS. 


Camphidenoxime or Camphoroxime, C,,H,,.N.OH, is formed when 
a concentrated aqueous solution of hydroxylamine hydrochloride 
is mixed with an alcoholic solution of camphor, sodium carbonate 
added until the reaction is alkaline and the solution diluted with 
alcohol and allowed to stand eight days. It is then precipitated 
with water or evaporated and the residue extracted with ether. 
On the evaporation of the latter, camphoroxime crystallizes out 
in white needles, while it separates from alcohol in transparent, 
sword-shaped prisms, which smell like camphor and also rotate 
on water. It melts at 115° and boils with slight decomposition 
at 249°—254°1 

Camphoroaime hydrochloride, C,)H,,N(OH)HCI, forms a white 
voluminous powder, which is only slightly soluble in water, 
readily in alcohol and acids. 

Sodium camphoroximate, C,,H,,N(ONa), is obtained by the 
addition of an alcoholic sodium solution to an ethereal solution 
of the oxime. It forms a white powder, which is only slightly 
soluble in cold, but readily in hot alcohol and water. 

Hihyl camphoroximate, C,,H,,N(OC,H,), is formed by heating 
the sodium salt with alcohol and ethyl iodide; it is a pleasantly 
smelling liquid, boiling at 208°—210°. 

Camphoroxime anhydride, C,,H,;N, is formed by the action of 
acetyl chloride on camphoroxime? and by allowing it to remain 
in contact with acids for some time.* It is a faintly smelling 
liquid, boiling at 216°—218°, which combines with hydroxy- 
lamine to form a substance of the formula C,,H,.N,O. This 
compound crystallizes in white plates, melts at 101° and dissolves 
in alkalis and acids. 

Lsocamphoroxime, C,,H,,NO, is prepared by heating the an- 
hydride with alcoholic potash ; it forms inodorous plates, which 
are slightly soluble in hot water, readily in alcohol, ether and 
strong acids,‘ melt at 125° and are not attacked by heating with 
methyl iodide and sodium ethylate.® It is reconverted into the 
anhydride by distillation with phosphorus pentasulphide. 

2519 Hydroxycamphor, C,,H,,0,, was obtained by Kachler and 
Spitzer by the action of sodium amalgam on an alcoholic 
solution of @-dibromocamphor,’ C,,H,,Br,0. Goldschmidt and 
Ziirrer then found that an isomeric compound is formed by 
boiling camphoroxime anhydride with alcoholic potash. This 


1 Niigeli, Ber, Deutsch. Chem. Ges. xvi. 497. 

2 Nigeli, zb7d. xvi. 2981. 3 Leuckart and Bach, zbid. xx. 110. 
4 Goldschmidt and Ziirrer, ibid. xvii. 2069. 

5 Nigeli, cbid. xvii. 805. 6 Monatsh. Chem. ili. 205. 


HYDROXYCAMPHOR. - 431 


they termed campholenie acid, but it was proved by Kachler and 
Spitzer to be identical with hydroxycamphor. It forms a faint 
yellow liquid, which boils at 265°, smells like turpentine and 
possesses weak acid properties. When its ammonium salt is 
heated to 250°, isocamphoroxime is formed. To explain this 
fact, Goldschmidt and Ziirrer look upon the iso-oxime as the 
amide of campholenic acid, camphoroxime anhydride being the 
corresponding nitril : 


Campholenic acid. Campholenamide. Campholene nitril. 


C,H,,.CO,H C,H,,.CO.NH, C.H,,.CN 


This appears, however, to be improbable, since, according to 
this view, camphor would simply be campholenaldehyde, C,H,,. 
CHO, whereas it is undoubtedly a ketone. The formation of 
all the compounds described above may be explained by the 
following series of equations : 


Camphor. Camphoroxime. 
vir J. OH. 
OC I + H,N.OH = C Fa + H,0. 
eae meager anhydride. 
melt aja! 
OHA HC | SN + 10. 
Isocamphoroxime. 


CO 
Ot | YN + 110 =F as 


\OHNH,. 
Hydroxycamphor, 
CO ead 
eS Ge NH, oo H,0 =C HC) KF NH, 
JP ay 
ot beg | ne as = thc | + P.O; + 5HLS. 


Goldschmidt and Ziirrer, to support their view that the 
anhydride is a nitril, adduce the fact that it combines with 


NOH 
hydroxylamine to form the amidoxime, CoH CO : 
NH 


2 


432 AROMATIC COMPOUNDS. 





The formation of this compound, however, may be simply 
explained in the following manner : 


: //O=NOH 
NN + H,N.OH = 6,H,< 


yb 
015 BF 14 
ei \CH.NH, | 


The isomerism of bornylamine and camphylamine may also 
be explained upon these lines. The former is obtained by 
replacing the oxygen of camphor by the amido-group and by 
the reduction of the oxime: 


Boers OH aD ye NH, 
SEE + 4H = C Ch | a H,0. 
2 


Camphylamine, on the other hand, is obtained by the action 
of hydrogen on the anhydride : 


O-. CH 
C,H |) NN 4H = 0,0, | 
\cH” \CH.NH,. 


The difference between these substances depends therefore on 
an isomerism of position, which is more clearly shown by the 
following formule : 


Bornylamine. Camphylamine. 
CH, CH, 
| | 
C C 
H,C” | \CH.NH, H,0”|\cuH, 
| | | 
HC, | OH, HC. | CH.NH, 
C C 
| | 
C,H, C,H, 


Camphorhydrazone, C,,H,,—N,H.C,H;, is formed when an 
alcoholic solution of camphor is treated with a solution of 
phenylhydrazine and sodium acetate and then heated. It is an 
oily liquid, which boils at 235°—243° at a pressure of 17 mm. 


1 Leuckart and Bach, Ber. Deutsch. Chem. Ges. xx. 104. 


CAMPHOPHENOL. 433 


and is decomposed by dry hydrochloric gas into aniline and 
camphoroxime anhydride :! 


O—N.NH.CH, on 
CHC ia is CHK | an + NH,.C,H, 
2 


Whilst in the formation of the substances hitherto described 
camphor acts as a ketone or camphidene oxide, it behaves in 
many cases as camphophenol : 


Camphidene oxide. Camphophenol. 
CH, CH, 
| | | 
C C 
H,0” | \co H,0” | \C.OH 
| | | 
H.C CH H,C H 
ys Na 
C C 
| | 
C,H, C,H, 


The latter does not exist in the free state, and we have there- 
fore a similar case to those of phloroglucinol and isatin, with 
the difference that in these the ketone form is the unstable one, 
while again in the case of carvol and carvacrol both forms exist. 

Sodium camphophenate, C,,H,,ONa, usually called sodium 
camphor, is formed, as already described, together with sodium 
bornylate by the addition of sodium to a solution of camphor in 
benzene or toluene. If the product be treated with ethyl 
iodide, a mixture of bornyl ethyl ether and ethyleamphor or ethyl 
camphophenate, C,,H,;.OC,H,, is formed. The latter is a liquid, 
which has a similar smell to camphor and boils at 226°—229°, 

2520 Chlorocamphor, C,,H,,ClO, was obtained by Wheeler by 
the action of hypochlorous acid on camphor. It separates from 
alcohol as a crystalline powder, melts at 95° and decomposes at 
200°. It is converted by the action of alcoholic potash into 
a hydroxycamphor, C,,H,,0,, which crystallizes in small 
needles, melting at 137°, smells like camphor and is volatile 
with steam.? 

Cazeneuve then found that when chlorine is passed into a 


1 Balbiano, Ber. Deutsch. Chem. Ges. xviii. Ref. 663 ; xix. Ref. 553. 
2 Ann. Chem. Pharm. exlvi. 73. 


434 AROMATIC COMPOUNDS. 


solution of camphor in absolute alcohol, two monochlorocam- 
phors are formed, one of which crystallizes from alcohol in long, 
white needles or large monosymmetric prisms, which melt at 
83°—84°. Jt smells like camphor, has an aromatic, bitter taste, 
boils at 244°—247° and is volatile with steam. The other modi- 
fication, which is formed in smaller quantity, forms microscopic 
crystals, melts at 100° and boils at 230°—237°. It is converted 
by treatment with alcoholic potash into the first modification, and 
Cazeneuve therefore assumes that the isomerism is of a physical 
nature. Nascent hydrogen reconverts chlorocamphor into 
camphor.’ 

Schiff and Puliti then treated an alkaline solution of cam- 
phocarboxylic acid (see below) with chlorine and obtained a 
chlorocamphor, which also crystallizes in large prisms, but does 
not melt until 93°—94°, its behaviour in other respects being 
however identical with that of Cazeneuve’s compound.? 

These two compounds are considered by Balbiano to be iden- 
tical, smce they are both converted by phenylhydrazine into 
camphineosazone, which is described below.2 They are also 
both converted into camphoric acid, C,H, ,(CO,H),, by oxidation. 

Dichlorocamphor, C,)H,,C1,0O, also exists in two isomeric forms, 
which are formed by the action of chlorine on an alcoholic 
solution of camphor and are physical isomerides (Cazeneuve). 
One of these crystallizes from alcohol in large, rhombic prisms, 
which melt at 93°, readily sublime and are only slightly soluble 
in cold alcohol, while the other is extremely soluble in alcohol 
and is therefore difficult to obtain in crystals. It melts at 77° 
and has a dextrorotation equal to that of the higher melting 
modification.‘ 

Trichlorocamphor, C,,H,,Cl,0, 1s formed by the action of 
chlorine on fused chlorocamphor. It forms small, white crystals, 
melting at 54°.° 

Bromocamphor, ©C,,H,;BrO. Laurent found that camphor 
combines with bromine to form the dibromide,® which is, how- 
ever, more readily obtained by employing a solution of camphor 
in chloroform.’ It crystallizes in orange-red prisms, which lose 
bromine in the air and on heating to 100° in a closed vessel 
decompose into hydrobromic acid and bromocamphor (Swarts). 
In order to prepare the latter, 30 parts of camphor and 32 parts 


1 Compt. Rend. xciv. 1530; xcv. 1358 ; ci. 438; Bull. Soc. Chim. xxxix. 501. 
2 Ber. Deutsch. Chem. Ges. xvi. 887. 3. lbid. xx, Ret, 216. 

4 Compt. Rend. xciv. 780, 1360. > Cazeneuve, ibid. cili. 551, 606. 

6 Ann. Chem. Pharm, xviii. 251. 7 Swarts, Jahresb. Chem. 1862, 462. 


BROMOCAMPHOR. 435 


of bromine are dissolved in 18 parts of chloroform, the latter 
distilled off after some hours and the residue washed with 
alcohol and recrystallized from ether.t It crystallizes in mono- 
symmetric prisms, isomeric with those of chlorocamphor,? which 
melt at 76° and smell like camphor. It is readily soluble in 
alcohol and ether, still more freely in chloroform and benzene. 
It boils at 274°? yields camphoric acid on oxidation and is 
reconverted into camphor by the action of nascent hydrogen or 
by heating with alcoholic potash, while sodium converts it into 
sodium camphophenate. It is not attacked by phosphorus 
pentachloride even at 100°. It follows from these reactions that 
bromocamphor has a constitution which resembles that of tri- 
bromophenol bromide (Pt. III. p. 116): 


C.OBr 
Vessels 


It is employed in medicine as a soporific in cases of hysteria, 
dipsomania, delirium tremens, &c. The isomeric chlorocamphors 
have the same action* and therefore an analogous constitution, 
this being also confirmed by the fact that they, as well as bromo- 
camphor, are converted into camphineosazone by heating with 


phenylhydrazine :° 


/Lobr 
CoH | + 2N,H,.C,H, = 
CH 
C—N,H.C,H, 
CsHi< | + HBr + H,O + H,. 
(i==N.ELO.H, 


It forms an amorphous mass, melting at 55°. 

Dibromocamphor, C,,H,,Br,0. Swarts found that this com- 
pound, which melts at 114°5°, is formed when monobromo- 
camphor is heated to 120° with bromine. According to other 
statements, it melts at 57°, and this is confirmed by Schiff, who 
assumes that the higher number was originally a printer’s error 


1 Keller, Jahesb. 1880, 726; see also Maisch, ibid. 1873, 499; Gault, zdid. 
1874, 538. 

2 Montgolfier, Ann. Chim. Phys. [5] xiv. 110; Cazeneuve and Morel, Compt. 
Rend. ci. 438. 

3 Perkin, Ann. Chem. Pharm. Suppl. iv. 125. 

4 Ber. Deutsch. Chem. Gles. xx. Ret. 291. 

5 Balbiano, cbid. xix. Ref, 553 ; xx. Ref. 215. 


436 AROMATIC COMPOUNDS. 


and has been copied from one text-book to another for about 
fifteen years. 

Kachler and Spitzer have however found that dibromo- 
camphor exists in two modifications.” 

a-Dibromocamphor is formed when monobromocamphor is 
heated for six to eight hours with the calculated quantity of 
bromine at 120°. It separates from the brown syrupy product 
on standing in the form of crystals, which are purified by 
recrystallization from alcohol. It may be obtained from petro- 
leum spirit in rhombic crystals, which melt at 61°, volatilize 
with steam and are converted into monobromocamphor and 
camphor by heating with alcoholic potash or by reduction. It 
is not attacked by phosphorus pentachloride and is converted 
into camphocarboxylic acid by the action of sodium and carbon 
dioxide. 

B-Dibromocamphor is obtained by heating the a-derivative 
or monobromocamphor with bromine for 10—12 hours to 
125°—130°. It crystallizes in rhombic tablets, melting at 115°, 
is only slightly volatile with steam and is also not attacked by 
phosphorus pentachloride. - On heating with alcoholic potash, 
it yields an oily mixture, while it is converted into camphor by 
the action of sodium on its ethereal solution. 

Iodocamphor, C,,H,,10, is formed by the action of cyanogen 
iodide on sodium camphor, and forms crystals, which are iso- 
morphous with those of chlorocamphor and melt at 43°—44°3 

2521 Nitrocamphor, C,,H,,(NO,)O, is obtained from the 
following compounds by treating them with alcoholic potash or 
acting upon them in ethereal solution with zinc and sulphuric 
acid. It is, however, most advantageous to boil the alcoholic 
solution with zinc upon which a thin layer of copper has been 
precipitated. Nitrocamphor crystallizes from alcohol in rhombic 
prisms, has a strong lavorotation and melts at 100°—101°° 
According to Schiff, it has the following constitution : 


0.0H 
C,H, | iH 
\G.no, 


It is a powerful, monobasic acid, and yields very characteristic 
salts, which have been investigated by Cazeneuve. ‘They are 


1 Ber. Deutsch. Chem. Gtes. xiv. 1378. 2 Monatsh. Chem. iii. 205. 

3 Haller, Compt. Rend. lxxxvii. 695. 

* Schiff, Ber. Deutsch. Chem. Ges, xiii. 1402 ; Schiff and Piluti, zb¢d. xvi. 889. 
> Cazeneuve, Bull. Soc. Chim. xlvii. 920; xlix. 92. 


NITROCAMPHOR. 437 


dextrorotatory and decompose on heating with production of a 
smell of myrrh. Those of the alkali metals and of magnesium 
are soluble in water. 

The zinc salt, [C,,H,,(NO,)O],Zn + HO, crystallizes from 
alcohol in large, six-sided, apparently rhombic tablets. The 
copper salt, [C,,H,,(NO,)O],Cu + H,O, is a chestnut brown 
precipitate, which forms a solution of this colour in alcohol, 
from which it separates in small, grass-green crystals. The 
ferrous salt forms garnet-red tablets, which are probably isomor- 
phous with the zinc salt, while the ferric salt is a blood-red 
precipitate, which imparts the same colour to alcohol. 

Nitrochlorocamphor, C,,H,,C]CNO,)O, is formed by the action 
of concentrated nitric acid on chlorocamphor, and crystallizes 
from alcohol in long needles, melting at 93°—94°. An isomeric 
compound is formed at the same time as a mass, which resembles 
camphor, melts at 83° and has a bitter aromatic taste. 

Nitrobromocamphor, C,,H,,Br(NO,)O, forms large, rhombic 
prisms and is isomorphous with the preceding compound and 
with dichlorocamphor.’’ It melts at 104°—105°, scarcely dis- 
solves in cold alcohol and is insoluble in alkalis, on which 
account Schiff has assigned the following formula to it : 


COBr 
CHC | NO, 


Amidocamphor, C,,H,;(NH,)O, is obtained by adding sodium 
amalgam to a solution of nitrocamphor in strong caustic potash. 
It is a thick, oily liquid, which boils at 246°4°, solidifies to a 
waxy mass on cooling, has a penetrating ammoniacal odour 
and an alkaline reaction and behaves in every respect as a 
primary amine. Its hydrochloride crystallizes in white needles. 

An isomeride of hydroxycamphor, dthydroxycamphene, is 
formed by the action of nitrous acid on the aqueous solution of 
this base : 

C.OH 


ne | +N,+ 5,0. 
C.OH 


C.OH 
OH ios + HONO C8 
\ONH, 


It is a crystalline mass, which melts at 154°—155° and is 
volatile with steam. 


1 Cazeneuve, Compt. Rend. ci. 488, 


438 AROMATIC COMPOUNDS. 








Camphimide, C,,H,,N, is formed by boiling the hydrochloride 


of amidocamphor with water : 


C.OH. C 
CHS <VYNH + 4,0. 
\Uan, AG 


This substance is isomeric with camphoroxime anhydride and 
forms an oily liquid, which smells like coniine and solidifies at a 
low temperature. When the solution of its hydrochloride is 
mixed at 0° with sodium nitrite solution, a compound is pre- 
cipitated, which crystallizes in large, yellow tablets, melting at 
73°—74°, and has the formula C,,H,,N,O. Schiff considers it 
to be a diazo-compound and not nitrosocamphimide, since it does 
not yield a hydrazine by the action of acetic acid and zinc dust, 
but is reconverted into amidocamphor. When it is heated to 
140°, HC ake or camphine oxide is formed : 


Gs 


= CH 
2 


C 
OE ide CHK IDO + Ne 

This is a crystalline substance, which melts at 160°, smells like 
camphor and volatilizes with steam.* 

Hydroxyisocamphor, C,,H,,0(O0H). The acetate of this com- 
pound is formed together with camphor, when bornyl acetate is 
oxidized in acetic acid solution with chromic acid. It crystallizes 
in prisms, melting at 69°, boils at 273°5° with slight decomposition 
and is converted by boiling with caustic potash into hydroxyiso- 
camphor, which remains on the evaporation of the ethereal solution 
as a crystalline mass. It has a faint odour of vanilla, sublimes 
readily and melts with decomposition at 248°—249°, It is oxidized 
by nitric acid to camphanic acid, C,,H,,O,, (p. 446).” 

Its constitution is probably expressed by one of the following 
formule : 


OH, CH, 
| | 
G G 
oc” | \CH.OH H,0” | \CH.OH 
| | | 
HC, | CH, OC. | CH, 
U U 
| | 
C,H, C,H, 


1 Schiff, Ber. Deutsch. Chem. Ges. xiv. 1375. 
2 Schrotter, Monatsh. Chem. ii. 224. 


ADDITION-PRODUCTS OF CAMPHOR. 439 


Addition-products of camphor. Wydrochloric acid, sulphur 
dioxide and nitrogen peroxide all combine with camphor to form 
liquid compounds, which are decomposed by water but have not 
hitherto been further investigated. 

Camphor hydriodide, C,,H,,0.1H, is obtained together with 
other products (p. 427), by heating camphor with iodine. It 
forms crystals, which fume in the air and rapidly deliquesce. | 

Camphor nitrate, (C,,H,,0),N,O;. This characteristic com- 
pound was first obtained by Brandes, who heated camphor with 
dilute nitric acid.’ It is formed, together with camphoric acid, 
when camphor is boiled with nitric acid of sp. gr. 137 im a 
retort, and distils over as an oily liquid, which has a sour but 
camphor-like smell, and is decomposed by water with separation 
of camphor, while dry potassium carbonate has no action upon 
it. It is volatile with nitric acid without decomposition, but 
decomposes to a very large extent when distilled alone, nitrous 
fumes being evolved. Its constitution is without doubt analogous 
to that of cinnamaldehyde nitrate : 


NO,.0 O.NO, 


No CO’ 


CHK Le ap Cote 


Camphor boronfluoride, C,,H,,0.BF;, is formed when boron- 
fluoride is passed into fused camphor. It crystallizes in needles, 
which melt at 70°.? 

Aldehyde camphor is produced when camphor is shaken up 
with a solution of aldehyde. It is an oily liquid, which readily 
loses aldehyde and is decomposed into its constituents by water. 
When camphor and chloral hydrate are triturated together, a 
thick liquid is formed, which has a pungent taste, dissolves in 
alcohol and chloroform and is decomposed by water.2 These 
compounds have probably the following constitution : 


SRG ERIER OES: » ZERO BIO Oe 
C.H | 8 i | 
SCH, CH, 
2522 Cyanocamphor or Camphonitril, C,,H,,O(CN), is obtained 
when cyanogen is passed into a hot solution of camphor in 


1 Schweigg. Journ. xxxviil. 257. 2 Landolph, Compt. Rend. 1xxxvi. 539. 
3 Cazeneuve, Bull. Soc. Chim. xxxiv. 209; xxxvi. 650. 


294 


440 AROMATIC COMPOUNDS. . 


toluene to which metallic sodium has been added. It crystallizes 
from ether in rectangular prisms, melts at 127°—128° and boils 
with decomposition at 250°. If it be dissolved in warm caustic 
soda solution, sodiwm cyanocamphophenate, C,,H,,(ONa)CN, 
separates out on cooling in fine needles, which are soluble in 
alcohol, but are decomposed by water. The potassium salt 
forms pearly tablets.’ 

Camphocarboxylic acid,C,,H,,0(CO,H). This compound was dis- 
covered by Baubigny and is obtained by dissolving 150 grams. of 
camphor in 500 ccms. of toluene, heating the solution to 90°, 
and finally adding 16 grams. of sodium and passing in carbon 
dioxide. The product is extracted with water and the solution 
allowed to stand, until the borneol, which is simultaneously 
formed, has separated out. It is then filtered, the concentrated 
solution decomposed with hydrochloric acid and extracted with 
ether. Impure camphocarboxylic acid remains on evaporation 
and is recrystallized from hot water, which must not be boiling.? 
It crystallizes from dilute alcohol in long, silky needles and from 
water and ether in monosymmetric prisms, which melt at 123°— 
124° and decompose into carbon dioxide and camphor when more 
strongly heated. It is also formed from dibrommocamphor by the 
action of sodium and carbon dioxide. 

Its.formation corresponds to that of salicylic acid from phenol, 
and since its nitril behaves as a phenol, we arrive at the following 
constitutional formule : 


C.0OH C.OH 
CC II CHC | 
C.ON C.CO,H 


Ethyl camphocarboxylate, C,)H,,(OH)CO,.C,H,;, was obtained 
by Haller, who saturated an alcoholic solution of the nitril with 
hydrochloric acid and allowed the whole to stand; it has also 
been prepared by Roser from the acid by the same method.’ It 
is a liquid, which smells like camphor and boils at 276°. 

Chlorocamphocarboxylic acid, C,,H,,Cl10.CO,H, is formed when 
a current of chlorine is passed into an alkaline solution of the 
acid. It separates on the addition of dilute hydrochloric acid in 
white crystalline flocks, which melt at 93°—94° with evolution 


1 Haller, Compt. Rend. lxxxvii. 843 ; cii. 1477. 
2 Kachler and Spitzer, Mowatsh. Chem. ii. 2338. 
3 Ber. Deutsch. Chem. Ges. xviii. 3112. 


OE —— es 


CAMPHOLIC ACID. 441 





of gas and decompose completely at 100° into chlorocamphor and 
carbon dioxide. 

Bromocamphorcarboxylic acid, C,)H,,BrO.CO,H, is obtained 
when the acid is treated with bromine at a low temperature. It 
is readily soluble in alcohol and ether and is precipitated by 
hydrochloric acid from its alkaline solution as a crystalline 
powder, which decomposes into carbon dioxide and bromo- 
camphor when heated to 65° or boiled with alcohol. 


OXIDATION PRODUCTS OF CAMPHOR. 


2523 Campholic acid, C,,H,,0,, was obtained by Delalande? 
by passing the vapour of camphor over potash lime heated to 
300°—400°. It is also formed by the continued boiling of 
camphor with alcoholic potash : 


OH, CH, 
| | 
C 
H,C” | \co H,C” | \cO.OK 
eee OK, SA 
sien igtonsy H. 
eigiAe73 2 aa 
U 
| | 
OH, C,H, 


It is best prepared, however, by adding sodium to a heated 
solution of camphor in a rock-oil boiling at 130°. Sodium 
bornylate and sodium camphor are simultaneously obtained, and 
constitute the chief product if a lower temperature be employed.* 
The mass which separates out is pressed and treated with water, 
which precipitates camphor and borneol, These are filtered off 
and the campholic acid precipitated by the addition of sulphuric 
acid. It is then finally purified by distillation and recrystall- 
ization.* 

It is scarcely soluble in cold water and crystallizes from dilute 
alcohol in long brittle prisms, but from a mixture of ether and 

1 Schiff and Puliti, Ber. Deutsch. Chem. Ges. xvi. 887 ; J. de Santos e Silva, 
bid, vi. 1092. 2 Ann. Chem. Pharm, xxxviii. 337. 


3 Malin, zbid. exlv. 201 ; Kachler, zbid. clxii. 259. 
Montgolfier, Ann. Chim. Phys. [5] xiv. 99. 


442 AROMATIC COMPOUNDS. 


alcohol in soft plates, which melt at 95°, readily sublime and 
volatilize with steam. 

Camphol chloride, C,,H,,OCI, is formed by the action of 
phosphorus pentachloride on the acid and is an oily liquid, which 
boils at 222°—226°. 

2524 Camphoric acid, C,,H,,0,. Kosegarten, whose Dassertatio 
de camphora et partibus quae eam constituunt appeared in the 
year 1785, endeavoured so far as possible to dephlogisticate 
camphor by repeated treatment with nitric acid and thus 
obtained an acid, which he found to resemble oxalic acid, but 
nevertheless considered it as a distinct substance. In 1793, 
Dorfurt concluded that this acid was benzoic acid, but this 
assertion was contradicted by Bouillon-Lagrange in 1799 and 
Bucholz in 1809. It was then investigated by many chemists 
and its composition finally determined by Malaguti, Liebig and 
Laurent.? 

Its power of dextrorotation was then observed by Bouchardat.? 
A levorotatory camphoric acid was then prepared by Chautard 
by the oxidation of levocamphor and was found to differ from 
the previously known modification only in the direction of its 
rotation of the plane of polarised light. These two substances, 
like the two tartaric acids, combine to form an inactive para- 
camphoric acid,? and camphoric acid is also converted into an in- 
active mesocamphoric acid by heating with water in a sealed tube, 
so that the analogy with tartaric acid is completely borne out. 

Camphoric acid is probably formed from camphor according to 
the following equation : 


OH, CH, CH, 
| | | 
C C C 
H,Cc” | \co H,0”|\co H,C”| \CO.OH 
ah | i t20 | | SOTHO | 
Ox | CH, Cr | CO HC. | CO.0H 
b 6 U 
| | 
C,H, C,H, C3H, 


It is also formed by the oxidation of campholic acid with 
concentrated nitric acid (Kachler). 


1 Ann. Ohem. Pharm. xxii. 38, 50 and 185. 
2 Jahresber. Chem. 1868, 556. 
3 Chautard, Ann. Chem. Pharm. exxvii. 121. 





———— 


CAMPHORIC ACID. 443 





In order to prepare it, camphor is distilled in a retort with 
ten parts of concentrated nitric acid and the distillate repeatedly 
replaced in the retort until all the camphor has dissolved and no 
further evolution of nitrous fumes occurs, fresh portions of nitric 
acid being added if necessary (Laurent). According to Wreden, 
150 grams. of camphor and two litres of nitric acid of sp. gr. 
1:27 are brought into flasks of four litres capacity, a conducting 
tube for the nitrous fumes being fastened in the neck by means 
of plaster of Paris. The mixture is heated on a briskly 
boiling water-bath until the vapours are only slightly coloured, 
the operation lasting for about 50 hours. The product is then 
converted into the sodium salt and this once recrystallized. 
About 725—805 grams. of pure camphoric acid are obtained 
from 1500 grms. of camphor.t 

It is readily soluble in alcohol; 100 parts of water dissolve 
0625 parts at 12° and 10 parts at the boiling point. It 
crystallizes in small plates or monosymmetric prisms, melting 
at 178°. On fusion with caustic potash isopropylsuccinic acid 
(pimelic acid) is formed. When it is heated with zine chloride? 
or with distilled hydriodic acid to 200°, tetrahydrometaxylene 
is obtained, while if the concentrated acid be employed, 
hexhydrometaxylene is formed.* Carbon dioxide and hydrogen 
are first eliminated, probably to some extent as formic acid, and 
since camphoric acid contains the isopropyl group, the formation 
of the so-called tetrahydrometaxylene then admits of a simple 
explanation : 


CH, | CH, 

| | 

C—CO0,H C 
H,0%| CH, H,0” | \CH, 

| | el | + CO, + CH,0O,. 

H,C\ | CH—CH, H,C\| CH—CH, 

U CH 

CO,H 


The conversion of this into hexhydrometaxylene then follows 
by the addition of hydrogen. 
Camphorates. The salts of the alkali metals are very readily 


1 Ann. Chem. Pharm. clxiii. 323. 2 Ballo, ibid. exevii. 321. 
3 Wreden, bid. clxxxvii. 156, 


444 AROMATIC COMPOUNDS. 


soluble and do not easily crystallize ; acid salts of these metals 
do not appear to exist. 

Caleium camphorate, C,,H,,0O,Ca + 9H,0, forms crystals, 
which are tolerably soluble in water; when its solution is boiled 
with camphoric acid, the acid salt, (C,,H,,0,),Ca, is formed and 
crystallizes in large prisms. 

Kemper has ae prepared the coreestorndine barium salts ; 
on the other hand only the normal magnesium camphorate ine 
been prepared. It crystallizes with varying amounts of water. 
The salts of most of the other metals are insoluble or only 
slightly soluble in water, The soluble salts have less rotatory 
power than the free acid, while the reverse of this is true in the 
case of malic acid, tartaric acid, aspartic acid and quinic acid.” 

Acid methyi camphorate, C,,H,,(CH,)O,, is formed by the 
distillation of camphoric acid with wood spirit and sulphuric 
acid. It is thus obtained as a viscid oil, which solidifies after 
some time in contact with water to a crystalline mass and 
crystallizes from alcohol in rhombic prisms, melting at 68°. Its 
alcoholic solution gives crystalline precipitates with lead acetate 
and copper acetate.® 

Normal ethyl camphorate, C,,H,,(C,H;),0, The acid ether is 
obtained by the distillation of camphoric acid with alcohol and 
sulphuric acid as a thick, colourless liquid, which decomposes on 
distillation into camphoric anhydride and the normal compound. 
This is an oily liquid, which boils at 285°—287° and has an 
unpleasant, almost unbearable smell and a very disagreeable, 
bitter taste. 

2525 Camphoryl oxide, C,,H,,0,. The anhydride of camphoric 
acid was obtained as early as the year 1799 by Bouillon- 
Lagrange from the acid by simple distiliation, and it was then 
further investigated by Malaguti and by Laurent. Gerhardt 
and Chiozza, who also examined it, found that it may be 
obtained by the action of phosphorus pentachloride on camphoric 
acid,® and Walter prepared it by dissolving the acid in sulphuric 
acid and precipitating with water.6 According to Maissen, an 
almost theoretical yield is obtained by boiling together equal 
molecules of acetic anhydride, anhydrous sodium acetate and 


1 Jahresber. Chem. 1862, 270 ; 1864, 402. 

* Hartmann, Ber. Deutsch. Chem. Ges. xxi. 221. 
Plsoars Ann. Chim. Phys. [8] xxxvii. 196. 

4 Ibid. lxiv. 152 ; Ann. Chem. Pharm. xxii. 32. 
5 Ibid. lxxxvii. 290, 

§ Ann. Chim. Phys. [8] ix. 177. 


CAMPHORYL OXIDE. 445 
camphoric acid,! the same result being obtained by heating the 
latter with acetyl chloride :? 


CO.0H 
CH 
Se ONCO.OT 


CO 
CHK >? + OH,,CO.0H + HCL. 


+ CH,.COCI= 


Several other methods of formation have already been 
mentioned. Camphoryl oxide is readily soluble in ether and 
crystallizes from alcohol in long needles or, on addition of 
benzene, in lustrous, rhombic prisms (Montgolfier). It melts at 
216°—217°, boils above 270°, readily sublimes in needles and is 
gradually reconverted into the acid by boiling water. 

Bromocamphoryl oxide, C,,H,,BrO,. This substance, which is 
usually known as bromocamphoric anhydride, is formed when 
camphoryl oxide is heated with bromine.? It separates from 
chloroform in large, compact, rhombic crystals, which melt 
at 215°, 

Camphoryl chloride, C,)H,,0,Cl,, is obtained by the action of 
two molecules of phosphorus pentachloride on one molecule of 
camphoric acid and is a yellowish liquid, which decomposes on 
heating and is gradually converted by water into camphoric 
acid. 

Gaseous ammonia converts it into a viscid mass of camphor- 
amide, C,)»H,,0,(NH,)., which becomes crystalline after some 
time.* 

Camphoramic acid, C,H,,(CO.NH,)CO,H. When a boiling, 
concentrated alcoholic solution of the anhydride is saturated 
with ammonia, ammonium camphoramate crystallizes out on 
cooling. This salt is dissolved in water and decomposed with 
hydrochloric acid. The free acid thus obtained crystallizes in 
transparent, rectangular prisms.° 


C,H tie \ W 
Camphorimide, NH, was obtained by Laurent b 
Bt Se A tort A Ms 


heating ammonium camphoramate. It crystallizes from alcohol 


1 Gaz. Chim. Ital. x. 286. 

2 Anschiitz, Ber. Deutsch. Chem. Ges. x. 1881. 

3 Wreden, Ann. Chem. Pharm. clxili. 330; Fittig and Woringer, ibid. 
ecxxvii. 1. 

4 Moitessier, 7bid. cxx. 252. 5 Laurent, zbid. lx. 320. 


446 AROMATIC COMPOUNDS. 


in six-sided tablets, sublimes at 150° and melts, when heated in 
a sealed tube, at 180°} 


os 
Camphorethylimide, CHS DN Cis is obtained by 
CO 


heating ethylamine camphorate and is a crystalline mass, which 
melts at 4'7°—48°, boils at 271°—273° and is converted by the 
action of phosphorus chloride into a crystalline chloride. This 
substance yields camphorethylimidethylimidine when acted upon 
by ethylamine : 


ane Coo Gn the 


Tuc we O,H,+H,N.C,H,=C MCS SN.CSH. + 2HCL 


This is an oily liquid, which boils at 285°—286°, has a faint 
narcotic odour and bitter taste, and acts as a strong base. It is 
decomposed by hydrochloric acid at 200° into camphorethyl- 
imide and ethylamine.? 

Paracamphoric acid is formed, as has been already stated, 
when concentrated solutions of dextro- and levocamphoric acid 
are mixed; a rise of temperature takes place and the para- 
acid separates out on cooling. It is less soluble than its 
isomerides and is also formed by the oxidation of the inactive 
camphor, which occurs in oil of lavender. | 

Mesocamphoric acid is obtained by heating camphoric acid to 
140° with fuming hydrochloric acid* as well as, accompanied by 
paracamphoric acid, by heating it with water to 180°—220°. 
It is more readily soluble in water than ordinary camphoric acid 
and crystallizes in soft, dull needles, which melt at 113°. 

2526 Camphanie acid, C,,H,,0, was obtained by Wreden on 
treating camphoric anhydride with bromine and boiling the 
product with water.© Kachler shortly afterwards obtained it by 
heating campholic acid with moist bromine.’ Wreden regarded 
it as hydroxycamphoric anhydride, but Fittig pomted out that it. 
exhibits all the properties of a lactonic acid, the formation of 
which, in this case, can be readily understood, on the assumption 


1 Ballo, Ann. Chem. Pharm. exevii. 334. 

2 Wallach and Kamenski, zbid. cexiy. 241. 

3 Chautard, ibid. exxiv. 121. 

4 Wreden, 2did. clxiii. 327. 

5 Jungfleisch, Ber. Deutsch. Chem. Gres. vi. 680. 
6 Ann. Chem. Pharm. clxiii. 330. 

7 Ibid. clxii. 264. 


CAMPHANIC ACID. 447 


that the brominated anhydride, which is the first product, is 
converted successively into bromocamphoric acid and hydroxy-. 
camphoric acid, the latter of which then passes into the lactone 
with elimination of water :1 


Br OH. 


fa fe 
OH COOH] HLO = HBrwtid Ho OF — 
SEeNCOGH 0 COOH 
0 
CHsAbo 4 H0. 
CO.0H 


The accuracy of this view was soon proved by Rudzinsky- 
Rudno, who prepared salts of the dibasic hydroxycamphoric 
acid.” 

In order to prepare camphanic acid, 10 grms. of camphoric 
acid are heated to 120° with 12 grms. of bromine, until the 
colour of the latter has disappeared, and the product boiled with 
water. In order to remove any unaltered camphoric acid, the 
barium salts are prepared and purified by recrystallization.® 

Camphanic acid is readily soluble in alcohol and ether ; it 
crystallizes from hot water in feathery forms or compact, 
monosymmetric prisms, melting at 200°. 

Barium camphanate, 2(C,,H,,0,),Ba + 7TH,O, forms large 
crystals. 

Hithyl camphanate, C,,H,,0,.C,H,, is obtained by passing hydro- 
chloric acid into an alcoholic solution of the acid, and crystallizes 
in thin prisms, which melt at 63° and readily sublime (Wreden). 

The constitution of camphanic acid is expressed by one of the 
following formule : 


CH, CO,H C,H, CO,H 
me nrg 
HC 0--C0-46.6,H, HO—0O--CO+0.GH} 
iaaaden a: 
GH, CH, 


If it be submitted to dry distillation, it partially decomposes 
with evolution of carbon dioxide into two isomeric substances, 
1 Ann. Chem. Pharm. elxxii. 151. 


2 Inauguwraldiss. Wiirzburg, 1879. 
3 Fittig and Woringer, dan. Chem. Pharm. cexxvii. 1. 


448 AROMATIC COMPOUNDS. 





the constitution of which, if the former of the above formule be 
assigned to camphanic acid, may be expressed as follows: 


Lauronolic acid. Campholactone. 
CH, CO,H CH, 
eA | 
C CH 
Bee) rae 5 ogy yee 
Ho OG CHa © HOO CO urs 
CH, CH, 


Lauronolie acid, C,H,,0,, is also formed, together with the 
lactone, by heating barium camphanate to 200° with water. It 
is an oily liquid, which is tolerably soluble in cold, readily in hot 
water and ether. It is partially converted into the isomeric 
lactone by dilute hydrochloric acid in the cold, more rapidly on 
heating ; the amount which undergoes this change never exceeds 
one half of the acid employed. 

Calcium laurolonate, (CjH,,0,),Ca + 3H,O, separates, when its 
solution is concentrated, in characteristic dendritic groups of 
small needles. 7 

Campholactone, C,H,,0,, crystallizes in small, colourless 
needles, which have a characteristic smell, resembling that of 
camphor. It melts at 50° and boils at 230°—235°. Its aqueous 
solution becomes turbid on heating, owing to the separation 
of oily drops, but is again rendered clear by a further rise 
of temperature. The inverse change takes place on cooling. 
Alkalis dissolve the lactone with formation of the corresponding 
hydroxy-acid, which is precipitated by the addition of acids at 0°, 
as an oil, which solidifies in small needles and is readily 
reconverted into the lactone (Fittig and Woringer). 

2527 Camphoronic acid, C,H,,0,4, is an oxidation product of 
camphoric acid and occurs in considerable quantity in the 
mother-liquors obtained in the preparation of the latter. It is 
readily soluble in water and alcohol, and crystallizes in dazzling 
white, microscopic needles or small, vitreous prisms, which melt 
at 136°—187°, and decompose on distillation into water and the 
anhydride, C,H,,0,;. The latter forms rhombic crystals and 
readily recombines with water to form the acid. This is 
tribasic and yields isobutyric acid on fusion with caustic potash." 


1 Kachler, Ann. Chem. Pharm. clix. 286 ; clxii. 262; exci. 148; Bredt, zbid. 
ccexxvi. 249. 


CAMPHOPHORONE. 449 


It must therefore be considered as <isopropylcarballylic acid, 
the formation of which from camphoric acid can readily be 
understood, and its constitution represented by one of the 
following formule : 


CH, CH; CH, CH; 
CH CH 


| | 
Cie 20 CH. CH. OH, = CH 
| | | | 


| | 
CO,H CO,H CO,H CO,H CO,H CO,H 











Camphophorone, CjH,,0. This substance was obtained by 
Gerhardt and Liés-Bodart! by the distillation of calcium cam- 
phorate and is also formed when camphor is heated to 100° with 
sulphuric acid.? It is a liquid which has an aromatic odour, 
boils at about 210° and is oxidized by chromic acid solution to 
acetic and adipic acids : 3 


CH,—C—CH, 

| i>CO CH,,.CH,.CO,H 

CH,—C +70 = | + CH;.CO,H + CO,. 
| CH,.CH,.CO,H 

CH,—C—CH, 


This substance appears to be identical with the zsophorone 
obtained, together with other products, by the distillation of 
cane * or grape-sugar ° with lime, and which is also formed from 
glycerol by a fungoid fermentation and by passing glycerol over 
a mixture of lime and zinc dust at a lowred heat. The phorone, 
which is formed by heating acetone with lime’ or sodium,’ also 
appears to be camphophorone, while that which is obtained by the 
action of hydrochloric acid on acetone (Pt. I. p. 578) is certainly 
a different compound (Kachler). 

Sulphocamphylic acid, C5H,,50, + 2H,0. This remarkable 
compound was obtained by Walter by heating camphoric acid 
with sulphuric acid, camphoric anhydride being, as already 


1 Ann. Chem. Pharm, )xxii. 293. 

2 Chautard, Jahresb. Chem. 1857, 483 ; Schwanert, Ann. Chem. Pharm. exxili. 
298. 3 Kachler, ibid. elxiv. 79. 

4 Fremy, ibid. xv. 278; Benedikt, zbid. clxii. 308. 

5 Lies-Bodart, zbid. ¢. 353. 

6 Schulze, Ber. Deutsch. Chem. Ges. xv. 64. 

7 Fittig, Ann. Chem. Pharm. ex. 32; exii. 309. 8 Stadeler, ibid. exi. 279. 


450 AROMATIC COMPOUNDS. 


mentioned, the first product.1 He named it sulphocamphorie acid 
and expressed its formation by the following equation : 


C,,H,,0, + H,SO, = C,H,,S0, + CO + H,0. 


Dumas explained the course of the reaction by supposing that 
the sulphuric acid residue replaced an atom of carbon, which 
had combined with one atom of oxygen of the sulphuric acid 
(Pt. I. p. 14). 

It is best prepared, according to Kachler, by dissolving cam- 
phoric anhydride in sulphuric acid, heating to 65° until no 
further evolution of carbonic oxide occurs and diluting with 
water. The solution is then extracted with ether, in order 
to remove camphoric and mesocamphoric acids, the excess 
of sulphuric acid neutralized with lead oxide, the filtrate 
treated with sulphuretted hydrogen and finally evaporated in 
a vacuum. 

Sulphocamphylic acid crystallizes in six-sided, asymmetric 
prisms,? which are readily soluble in water. It is a strong, 
dibasic acid, the constitution of which is still quite unknown. 
On fusion with potash, the compound C,H,,O, is formed, and 
separates from alcohol in monosymmetric crystals, melting at 
148°; it dissolves in alkalis and is reprecipitated without change 
by the addition of acids. 

Damsky, who wished to investigate this substance, was unable 
to prepare it, but obtained an isomeric compound. This melts 
at 99° and is a well-defined acid, which forms crystallized salts 
and decomposes on distillation with soda lime into carbon dioxide 
and the hydrocarbon C,H,,. The latter is a pleasantly-smelling 
liquid, which boils at 133°—135° and absorbs oxygen from the 
air, with formation of a viscid mass. 


LIMONENE GROUP. 


2528 Limonene, C,,H,,, is, according to Wallach, a terpene, 
first found in the rind of the fruit of the Agrumi (oranges, 
_lemons, &c.), and from which the following ethereal oils were pre- 
pared on the large scale by the Arabians as early as the sixteenth 
century, if not still earlier. 


1 Ann. Chim. Phus. [3] ix. 177. 2 Ann. Chem. Pharm. elxix. 178. 
3 Juhresb. Chem. 1877, 642. 4 Ber. Deutsch. Chem. Gles. xx. 2959, 


LIMONENE GROUP. 451 





Oil of lemon is prepared from the lemon, Citrus limonum. In 
Messina and Palermo the fresh rinds are pressed against a 
sponge, which receives the oil, and when saturated with it, is 
forcibly wrung by the workman, the contents being received in 
an earthen bowl. In Nice and Mentone the fresh fruit is 
rubbed over brass pins, which are fastened vertically in a vessel 
“ Eeuelle & piquer,’ and the oil (Lssence de citron a zeste) collected 
in a tube with which the bottom of the vessel communicates. This 
tedious hand work has been partially replaced by Monfalcone’s 
“ Strizzatore termopneumatico,” driven by a small steam engine. 
This machine consists of a double-walled drum of sheet iron, 
which is rapidly rotated and thus forces the fruit against pins 
placed along the walls. An oil of poorer quality (Hssence de 
citron destillé) is obtained by distilling the peel with water. 

Oil of orange peel is prepared in the same way in Sicily and 
Southern France from the rind of the unripe fruit of Citrus 
Bigaradia, which yields the finest oil (Hssence de Bigarade), while 
that obtained from Citrus Awrantiwm (Essence de Portugal) is less 
valuable. 

Oil of bergamot, which is a highly-prized perfume, is obtained 
from the scarcely ripened fruit of Citrus bergamia, a tree which 
is cultivated near Reggio in Calabria. This perfume is first 
mentioned in the year 1688 in the inventory of an apothecary 
in Giessen.1 

According to Tilden, oil of lemons contains as chief constituents 
levopinene and citrene, accompanied by other substances. The 
latter is, as was found by Wallach, identical with hesperidene, the 
chief constituent of oil of orange peel. The same terpene, 
which he calls limonene, also occurs in oil of bergamot, oil of 
neroli, oil of nutmeg, oil of elder flowers, oil of pine needles, and 
oil of erigeron (Zrigeron canadense). It is further identical with 
carvene, Which occurs with carvol in oil of caraway and oil of dill. If 
these two be separated by fractional distillation and the adhering 
carvol then removed by means of phenylhydrazine, the carvene 
retains the characteristic odour of the seeds, which is however con- 


1 Further information about this oil may be found in Fliickiger’s Pharma- 
kognosie and in Pharmacographia by Fliickiger and Hanbury. It is stated in a 
small work Le Parfumeur Frangots, par Le Sieur Barbe, parfumeur, 1693, that 
oil.of bergamot is extracted from the fruit of a lemon, which has been grafted 
on a bergamot pear. The name of the latter is derived from the Turkish 
beg-drmadi, the prince of pears. Volkamer, in his Hesperides Norimbergenses, 
1713, further describes limon bergamotta as ‘‘ gloria limonum et fructus inter 
omnes nobilissimus,” and mentions that the Italians prepare one of the finest 
essences from it. 


A452 AROMATIC COMPOUNDS. 


verted into that of oil of lemon when the carvene is shaken up 
with potassium permanganate and dilute sulphuric acid. 

Limonene has the sp. gr. of 0°846 at 20°, boils at 175°—177°, 
is dextrorotatory and is converted by heating to 250°—270° 
into dipentene, a portion being simultaneously polymerized ; 
dipentene is also formed from it by the action of hydrochloric 
acid (p. 456). 

Limonene tetrabromide, C,,H,,Br,, is prepared from the terpene 
by diluting one volume of this with four of ether and four of 
alcohol, cooling with ice and gradually adding 0°7 volumes of 
bromine, care being taken not to allow the temperature to rise too 
high. The solution is then allowed to evaporate in a basin, 
when, if the hydrocarbon was pure, crystals soon separate out. 
The alcohol is added to keep the oily by-products, which are always 
formed, in solution, while the tetrabromide is almost insoluble 
in it. It is also readily formed by the addition of bromine to a 
solution of limonene in ten parts of glacial acetic acid, and 
separates in hemihedral, rhombic, soft and pliable crystals, which 
melt at 104°—105°7 and are more soluble in ether than dipentene 
bromide ; the solution is also dextrorotatory. 

Limonene nitrosochloride, C,,H,,NOCI, is obtained by passing 
nitrosyl chloride into a mixture of one part of oil of orange peel 
and five parts of methylated spirits, cooled to —10°. It thus 
forms a crystalline precipitate, which melts at 103° and is thus 
converted into carvoxime.? 

2529 Carvol, C,,H,,O, occurs, as has already been mentioned, 
in oil of caraway (Carum carvi), together with limonene, from 
which it may be separated by fractional distillation. In order 
to obtain it perfectly pure, the fraction of the oil which boils 
above 190° is treated with an equal volume of alcoholic am- 
monium sulphide ; after some time the compound (C,,H,,0),SH, 
separates in long needles, which are decomposed by alcoholic 
caustic potash with separation of carvol.* It also occurs in oil of 
fennel (Anethum foeniculum)® and in oil of dill (Anethum 
graveolens). It is a liquid, which smells lke caraway, boils 
at 224°—225°, and is dextrorotatory, while a laevorotatory 
carvol is obtained from the oil of mentha crispa.® Both of these 


1 Wallach, Ann. Chem. Pharm. cexxvii. 277. 
2 Journ. Chem. Soc. xxxi. 558. 
3 Volkel, Ann. Chem. Pharm. lxxxv. 246. 
4 Varrentrapp, Handwéorterb. iv. 686. 
5 Nietzki, Newcs Handwérterb. ii. 986. 
4 ; tied Ler. Deutsch. Chem, Ges. xvi. 1887 ; see also Fliickiger, ibid. xvii. 
ef. 358. 


CARVOL. 453 


modifications are readily converted into the isomeric carvacrol 
(p. 454). 

Carvorime, C,oH,,(N.OH), was first obtained by Tilden and 
Shenstone by heating limonene nitrosochloride, and was named 
by them nitrosohesperidine. It is more readily formed when 
the chloride is heated with alcohol, and is also obtained by the 
action of hydroxylamine on carvol. It crystallizes from alcohol 
in large, transparent tablets, which melt at 71° and are con- 
verted by heating with an alcoholic solution of sodium methylate 
and methyl iodide into the methyl ether, C,,H,,(NOCH,), 
which is a colourless liquid and has a smell resembling that 
of carrots. | 

The benzoyl ether, C,,H,,(NO.CO.C,H,), is prepared by the 
action of benzoyl chloride; it crystallizes from hot petroleum- 
spirit in lustrous needles, melting at 95°. 

Carvolhydrazone, C,)H,,(N,H.C,H;), crystallizes from alcohol in 
fine needles, melting at 216° 

Hydrochlorocarvol, C,,H,;ClO, is formed, as observed by 
Varrentrapp, when hydrochloric acid passed into carvol, as: an 
oily liquid. It is converted by hydroxylamine into hydrochloro- 
carvoxime, C,,H,,Cl(NOH), which is also obtained by the 
combination of hydrochloric acid with carvoxime and crystallizes 
in tablets, melting at 132°. It is isomeric with limonene nitroso- 
chloride, from which it differs by its solubility in cold caustic 
soda solution, in which the latter is quite insoluble. The nitro- 
sochloride is also not attacked by benzoyl chloride, which readily 
converts hydrochlorocarvol into the benzoic ether, C,,H,,Cl 
(NO.CO.C,H,), which crystallizes from petroleum-spirit in lustrous 
needles, melting at 114°—115°? 

Carveol or Carvyl alcohol, C,)H,..OH, is formed by the action 
of sodium on an alcoholic solution of carvol and is a some- 
what viscous liquid, which has an odour different from that of 
carvol, boils at 218°—220, and is converted by acid chlorides 
into liquid ethers.’ 

Carvylamine, C,,H,;.NH,, is obtaimed by treating an alcoholic 
solution of carvoxime with glacial acetic acid and sodium amalgam. 
It is a liquid, which has an aromatic and ammoniacal odour, 
rapidly absorbs carbon dioxide from the air and forms a crystal- 
line hydrochloride, which is converted by sodium nitrite into 
carveol (Goldschmidt and Kisser). 


1 Goldschmidt and Ziirrer, Ber. Deutsch. Chem. Ges. xviii. 1729, 2220. 
2 Goldschmidt and Kisser, ibid. xx. 486. 3 Leuckart, ibid. xx. 114. 


454 AROMATIC COMPOUNDS. 








The constitution of the members of this group can readily be 
understood. Carvol is a ketone and stands in close relation 
to carvacrol or orthocymophenol. It is derived from limonene, 
which is a dihydrocymene, by the replacement of two atoms 
of hydrogen by one of oxygen. Both are optically active and 
therefore an asymmetric carbon atom must be present. The 
following formule are thus arrived at: 


CH, CH, CH, 
| | | 
CH. CH smn G, 
HC” \CH, HC” \co HC’ \c.oH 
| | | | | | 
Bos Jeu ae jek Eee Joi 
C C C 
| | | 
C,H, C,H, C,H, 
Limonene. Carvol. Carvacrol. 


Hence carvacrol stands in the same relation to carvol as 
phloroglucinol to triketohexhydrobenzene, the latter being how- 
ever unknown in the free state. 

The fact that limonene contains two double linkings is also 
proved by its specific refraction. 

Anthemol or Anthemyl alcohol, C,)H,,,0H, occurs as the 
angelic or tiglic ether in cumin oil and is a thick liquid, 
which smells like camphor, boils at 213°5°—214°5° with slight 
decomposition and is oxidized by boiling dilute nitric acid to 
paratoluic and terephthalic acids? It may perhaps be a 
derivative of limonene, and would in that case probably have the 
following constitution : 


CH,OH 


1 Brihl, Ber. Deutsch. Chem. Ges. xxi. 145. 
2 Kobig, Ann. Chem. Pharm. excy. 92. 


DIPENTENE GROUP. 455 





DIPENTENE GROUP. 


2530 Dipentenc, C,,H,, Wallach and Brass, by the action of 
hydriodic acid on cineol, C,,H,,0, a substance which is mentioned 
below, obtained a di-iodide, C,,H,,I,, which on heating with 
aniline yielded a terpene, which they termed cynene,' the name 
being changed by Wallach at a later date into cinene. This 
substance is identical with cajeputene, which is obtained by 
heating oil of cajeput with phosphorus pentoxide,’ and also 
with Berthelot’s csoterebentene, which is formed, together with 
polymerides, by heating oil of turpentine to 250°—270° and is 
obtained in a similar manner from all pinenes and from limo- 
nene, so that it is contained in Swedish and Russian oil of 
turpentine, which is prepared from pinewood-tar. It is further 
identical with caoutchin, obtained by the distillation of caout- 
chouc and gutta-percha. In addition to these substances, 
isoprene, C,H,, is formed by the same process and is converted by 
heat into a terpene, which was named di-tsopropene or terpilene? 
and, as was shown by Wallach, is also cinene. The divalerylene 
obtained from valerylene, C;H,, is also probably identical with 
this hydrocarbon. On account of this method of formation, the 
name of dipentene was given by Wallach to cinene.® It forms 
the chief constituent of the terpene, which Bauer and Verson 
obtained by heating rutylene dibromide, C,,H,,Br,, with alco- 
holic potash ® and of that which was prepared by Radziszewski 
and Schramm by converting the fraction of commercial amy- 
lene, which boils between 37°—39°, into the hydrochloride, 
C,H,,Cl(OH), heating this with ammonia and treating the 
hydroxyamylamine thus formed with phosphorus pentoxide :? 


2C.H,,(NH,)OH = C,,H,, + 2NH, + 2H,0. 


Dipentene is also formed with elimination of water from 


terpine, C,,H,,(OH),, terpineol, C,,H,,(OH) and cineol, C,)H,,0, 


1 Ann. Chem. Pharm. ecxxv. 299. 

* Schmidt, Jahresber. Chem. 1860, 481. 

3 Tilden, Jowrn. Chem. Soc. xlv. 410; Bouchardat, Compt. Rend. lxxx. 1446; 
lxxxvil. 657 ; lxxxix. 361 and 1117. 

4 Bouchardat, Bull. Soc. Chim. xxxill. 24. 

> The hydrocarbons, C;H,, are however called pentines, while the name pentene 
is synonymous with pentylene or amylene. 

6 Ann. Chem. Pharm. cli. 52. 

7 Ber. Deutsch. Chem. Ges. xvii. 838. 


295 


456 AROMATIC COMPOUNDS. 


which will be subsequently described. It is best prepared from 
its dihydrochloride, C,,H,,Cl,, which is obtained by the action of 
hydrochloric acid on the compounds just mentioned or by direct 


combination with limonene or moist pinene. The chloride is 


boiled with one part of anhydrous sodium acetate and two parts 
of glacial acetic acid for half an hour in a flask provided with 
an inverted condenser, the product distilled with steam, boiled 
with caustic potash, redistilled, dried and finally purified by 
fractional distillation.* 

Wallach detected it in considerable quantity in the ethereal 
oil of the camphor tree; this is the more remarkable as it has 
hitherto not been found in any other natural product. According 
to Brithl, however, it appears to occur in oil of cascarilla. 

Dipentene and its derivatives are optically inactive; it boils 
at 180°—182°, has a pleasant odour of lemons and a sp. gr. 
of 0°8538 at 16°. On agitation with concentrated sulphuric acid, 
it is partially converted into a resin, sulphur dioxide is evolved 
and cymene separates out on the addition of water. This hydro- 
carbon is also formed when dipentene is heated with phosphorus 
pentachloride (Wallach and Brass), a reaction which supphes the 
explanation of previously conflicting statements. Vélkel ob- 
tained cynene from oil of wormseed or impure cineol and purified 
it by means of sulphuric acid;* according to Griibe, the same 
hydrocarbon is formed by the action of phosphorus pentasulphide 
on the oil,? while Faust and Homeyer stated that cymene is thus 
obtained.‘ 

The latter is also formed by the action of concentrated sul- 
phuric acid on oil of turpentine, this being first converted into 
dipentene, which is also obtained when oil of turpentine is 
boiled with alcoholic sulphuric acid, but is partially converted 
into terpines and other products if the boiling be continued for 
some time. 

Dipentene tetrabromide, C,,H,,Br,, was first obtained by 
Wallach and Brass from cineol; it is prepared from dipentene 
in a similar manner to limonene tetrabromide ; like this it forms 
rhombic crystals, which, however, are less soluble in ether than 
those of the limonene derivative and always show the macro- 
dome but never a hemibhedral face. In addition to this, 


1 Wallach, Ann. Chem. Pharm. ecxxxix. 1. 
2 Ibid. Ixxxix. 358. 

3 Ber. Deutsch. Chem. Ges. v. 680. 

4 Ibid, vii. 1429, 


8 a 


DIPENTENE COMPOUNDS. 457 





they melt at 125°—126°, are very brittle and show reed-like 
striations on faces of the vertical zone. Dipentene may be 
‘readily detected in mixtures by means of this characteristic 
compound. 

253t Dipentenylene glycol, C,,H,,(0H), + H,O. Geoffroy, in 
the year 1727, observed the presence of crystals in an old 
specimen of oil of turpentine, which were taken by Buchner 
for the succinic acid salt of a volatile base. Dumas and Peligot 
investigated the substance and found that this o7/ of turpentine 
camphor is a hydrate, C,,H,, + 3H,O, and that it also occurs 
in basil-camphor (Ocymum basilicum) and the oil of Hletaria 
cardamomum.* 

Wiggers then discovered a method for obtaiming this interesting 
substance from turpentine in any wished for amount. “In the 
neighbourhood of Bremen a mixture of oil of turpentine, alco- 
hol, nitric acid and an extremely small quantity of oil of sassafras 
is largely employed by veterinary surgeons. The occurrence of 
crystals in this mixture has been observed by Herr Martfeld, 
dispenser to an apothecary in Otterberg near Bremen, and in 
September 1839 he forwarded me a small portion for examina- 
tion.” These proved to be the so-called turpentine-camphor 
and are formed, as shown by Wiggers, in large quantities when- 
ever a mixture of oil of turpentine, alcohol and nitric acid is 
allowed to stand;? a detailed account of the best method of 
preparation has also been given by the same author. He found 
that one molecule of water is lost on fusion, and this is considered 
by List to be water of crystallization, since it is also lost over 
sulphuric acid. Since the other two molecules of water are 
more firmly combined, the name hydrate of oil of turpentine 
appeared to him to be inadmissible, and as that of turpentine- 
camphor was obviously unsuitable, he took advantage of the 
name terpine, which had been proposed by Berzelius, and termed 
the substance terpine hydrate.4 

Deville then found that the same compound may also be 
obtained from oil of lemon and oil of bergamot.® 

In order to prepare dipentenylene glycol, which is the most 
suitable name for this compound, eight parts of oil of turpentine 
are mixed with two parts of alcohol and two parts of nitric acid 
of sp. gr. 1:°25—1°30 in flat basins.® After a few days the mother- 

1 Ann. Chem. Pharm. xiv. 75. 2 Ibid. xxxiii. 358. 


8 Ibid. \vii. 247. 4 Ibid. \xvii. 362. 
5 Ibid. lxxi. 348. § Hempel, ibid, clxxx. 71. 


458 AROMATIC COMPOUNDS. 


liquor is poured off from the crystals, which have already 
separated and is neutralized with an alkali, after which treatment 
another crop of crystals separates out.1 The preparation only suc- 
ceeds at the cool seasons of the year, as in summer a resinous mass 
is usually obtained.? According to Tilden, one volume of nitric 
acid of sp. gr. 1'4is mixed with one volume of strong alcohol 
and half a volume of rectified oil of turpentine, the mixture 
allowed to stand for two days, until all the smell of turpentine 
has vanished, and then poured into flat dishes, alcohol being 
added from time to time; about one-third of the oil of tur- 
pentine is thus converted into glycol and a still larger yield 
may be obtained by continuing the operation.2 The American 
and French oils of turpentine may both be employed for its 
preparation, while it cannot be obtained from the terpenes of the 
various species of Citrus (Tilden). 

Dipentenylene glycol crystallizes in large, transparent, mono- 
‘symmetric prisms,* which dissolve in 200 parts of cold and 22 parts 
of boiling water® and are still more readily soluble in alcohol. 
When it is heated in a capillary tube, it commences to fuse 
above 100° and melts at 116°—117° to a clear liquid, the fusion 
being accompanied by frothing and the sublimation of a small 
portion of the substance into the cooler portion of the tube. On 
distillation, the water of crystallization is first lost and the 
anhydrous compound then boils at 258° and solidifies on cooling 
to a hard mass, melting at 102°, which is very hygroscopic and 
readily combines with water, but not with bromine. 

2532 Dipentenyl oxide or Cineol, C,,H,,0, is the chief con- 
stituent of oil of wormseed.? When it is cooled by a freezing 
mixture and treated with hydrochloric acid, the compound 


(C,,H,.0),HCI, separates out in deliquescent crystals, which are — 


decomposed by water. The pure compound is obtained by a 
repetition of this operation and is then distilled with water and 
heated with alcoholic potash to remove adhering hydrochloric 
acid, after which it is again distilled with steam.” 


1 Wallach, Ann. Chem. Pharm. cexxvii. 284. 

2 Ibid. ecxxx. 248. 

3 Jowrn. Chem. Soc. xxxiii. 247. It is stated in Jahresber. Chem. 1878, 638, 
that Tilden used methyl alcohol, while he actually employed methylated spirits. 

4 Rammelsberg, Pogg. Ann. lxiii. 570. 

5 Blanchet and Sell, Ann. Chem. Pharm. vi. 268. 

6 Wormseed consists of the unexpanded flower-buds of Artemisia maritima, 
a shrub which is indigenous to South-Eastern Russia and Central Asia. Its 
name, Semen cynae, is derived from the Italian semenzina, the diminutive of 
semenza (seed), and is therefore more correctly written Semen cinae (Fliickiger). 

? Wallach and Brass, Ann. Chem. Pharm. cexxyv. 291. 


CINEOL. 459 


Cineol is identical with cajwputol, which is the chief con- 
stituent of oil of cajeput,) and with euwcalyptol,? and occurs in 
conjunction with ordinary camphor, C,,H,,O, and Borneo 
camphor, C,,H,,0, in oil of rosemary? and oil of spike,* this 
occurrence being especially remarkable because these three 
compounds had not previously been found together. 

Cineol is a liquid, which has a pleasant smell, resembling that 
of camphor, is optically inactive, boils at 176°—177° and solidifies 
when at a low temperature to crystals, melting at — 1°; its sp. 
er. at 16° is 0°923. When it is agitated with a concentrated 
solution of iodine in potassium iodide, a pasty mass is formed 
containing greenish, lustrous plates, which after drying on a 
porous plate rapidly deliquesce.® The presence of cineol in oil 
of rosemary may be detected by this reaction (Weber). 

Cineol also combines with hydrobromic and hydriodic acids, 
and is converted by the continued action of the latter into 
dipentenylene iodide. It unites with bromine to form cineol 
dibromide, C,,H,,.Br,O, which crystallizes in red needles or 
prisms, and readily decomposes into water, bromine and di- 
pentene, one half of this last combining with the bromine 
to form the tetrabromide. It combines with iodine to form 
the compound, C,,H,,I,O, crystallizing from petroleum-spirit 
in long, dark needles, which are more stable than those of the 
bromide. 

If cineol be heated with alcoholic sulphuric acid, it is con- 
verted into terpinene and terpinolene.® It is not attacked by 
sodium, nor by benzoyl chloride below 120°, while above this 
temperature hydrochloric acid, dipentene and benzaldehyde are 
formed. It does not combine with hydroxylamine and phenyl- 
hydrazine. It is therefore neither a ketone nor an alcohol, but 
appears to stand in the same relation to dipentenylene glycol as 
ethylene oxide to its glycol. 

1 Wallach, Ann. Chem. Pharm. ecxxv. 316. Oil of cajeput is obtained in 
the Dutch East-Indian Island Bouro by the distillation of the leaves of the Kayu- 
puti (the white-wood tree, Melaleuca Lewcadendron) and is first mentioned by 
Rumphius. It became known in Germany at the commencement of the eighteenti: 
century and was quoted in the tariffs of several apothecaries, while it was first 
employed in England in the present century (Fliickiger and Hanbury). 

2 Jahns, Ber. Deutsch. Chem. Gres. xvii. 294. Eucalyptol is the chief con- 
stituent of the ethereal oil of Hucalyptus globulus and probably also of Z. oleosa. 
These oils are imported from Australia and are chiefly employed for the adultera- 
tion of other ethereal oils, but have also a limited application for medicinal 
purposes. 3 Weber, Ann. Chem. Pharm. ccxxxviii. 90. 

4 Voiry and Bouchardat, Compt. Rend. cvi. 351. 


5 Kraut and Wahlfors, dun. Chem. Pharm. exxvili. 294. 
6 Wallach, zbid. ccxxxix. 22. 


460 AROMATIC COMPOUNDS. 


2533 Dipentenylene chloride or Terpene dihydrochloride, 
C,,H,.Cl, Thenard observed that oil of lemon combines with 
hydrochloric acid. The compound thus obtained was investi- 
gated by Blanchet and Sell, who described it as hydrochloride of 
otl of lemon,! while Dumas named it camphor of oil of lemon.? 
List then obtained terpine hydrochloride by the action of hydro- 
chloric acid on terpine hydrate, and stated that it is isomeric 
with oil of lemon camphor,® while Deville contended that the 
two substances are identical.4| Oppenheim found that the same 
compound is formed when terpine is treated with the chlorides of 
phosphorus,’ and Berthelot then observed that it may also be 
obtained by allowing oil of turpentine to stand in contact with 
concentrated hydrochloric acid for a month or by saturating a 
solution of the oil in alcohol, ether or acetic acid with hydro- 
chloric acid. Pinene hydrochloride is also formed by the last 
method,® but not when alcohol is employed (Flawitzky).’ 

Berthelot also stated that the chlorides obtained from oil of 
turpentine and oil of lemon are identical, and this was confirmed 
by Tilden, who found that the same chloride is also formed from 
many other terpenes. These are first converted, as was shown 
by Wallach, into dipentene, which readily forms the chloride 
when hydrochloric acid is passed into its ethereal solution,’ or 
more simply when a saturated solution of hydrochloric acid in 
glacial acetic acid is brought into contact with a solution of 
dipentene or limonene in acetic acid.1? It crystallizes in rhombic 
tablets, which melt at 49°—50°, and passes into the glycol when 
it is allowed to remain in contact with dilute alcohol” It has 
already been mentioned that a mixture of this hydrochloride 
with pinyl chloride forms a mixture of low melting point; 
such a mixture containing equal parts of the two compounds is 
liquid at the ordinary temperature and only solidifies at the 
freezing point of water. 

It is readily soluble in alcohol, but separates out as an oil 
when the solution is heated. According to early statements, 
oil of lemon sometimes yields a liquid instead of a solid chloride 
by the action of hydrochloric acid. This admits of a simple 


1 Ann. Chem. Pharm. vi. 282. 2 Ibid. ix. 61. 

3 Tbid. |xvii. 862. 4 Ibid. |xxi. 351. 

5 Bull. Soc. Chim. iv. 85. -6© Ann. Chem. Pharm, Ixxxiv. 350. 
? Beilstein’s Handbuch, 1773. 8 Ber. Deutsch. Chem. Ges, xii. 1181. 


9 Ann. Chem. Pharm. ccxxvii. 294 &e. 
10 Wallach, ibid. cexxxix. 3. 
11 Flawitsky, Ber. Deutsch. Chem. Ges. xii. 2358. 


DIPENTENE COMPOUNDS. 461 


explanation, since dipentenylene chloride is partially converted 
into terpinene by heating with alcohol or water, and the liquid 
chloride of this is an excellent solvent of the solid compound 
(Wallach). | 

When dipentenylene chloride is heated with a trace of ferric 
chloride, it becomes coloured a bright violet and finally blue.* 

Dipentenylene bromide, C,,H,,Br,, was obtained by Oppenheim 
in an impure state by the action of phosphorus tribromide on the 
glycol, whilst Hell and Ritter prepared it by passing hydrobromic 
acid into well-cooled oil of wormseed.? It is best prepared by 
saturating glacial acetic acid with hydrobromic acid and adding 
a solution of limonene or dipentene in glacial acetic acid, the 
bromide separating out immediately. It is also formed when 
the glycol is agitated with hydrobromic acid (Wallach). It 
resembles the chloride very closely and melts at 64°. 

Dipentenylene rodide, C,,H,.1,, was also obtained by Oppenheim 
in an impure state by the action of phosphorus tri-iodide on the 
glycol, and was prepared by Wallach and Brass, as already 
mentioned, from cineol and hydriodic acid. It is also readily 
formed when the glycol is agitated with concentrated hydriodic 
acid 3 and when limonene or dipentene are treated with hydriodic 
acid in acetic acid solution. It decomposes with great readiness, 
but becomes more stable as its purity increases. It crystallizes 
from petroleum-spirit in transparent rhombic prisms, which 
melt at 77°, or sometimes in monosymmetric tablets, melting at 
78°—79°. It changes when kept for some time, more rapidly 
when heated, into a deep brown liquid, the formation of which 
may be much delayed by preserving it under water in which 
a piece of phosphorus is placed. 

2534 Terpineol or Dipentenyl alcohol, C,,H,,O0H. Wiggers, 
by the action of hydriodic acid on terpine hydrate, obtained the 
compound 2C,,H,, + H,O, which was investigated by List and 
named ¢erpinol.® It is also formed when terpine hydrate is 
boiled with hydrochloric acid, very dilute sulphuric acid, 
potassium sulphate, &c., and is a colourless, strongly refractive 
liquid, which boils at 168° and, especially when diluted, has a 
pleasant smell of hyacinths. Oppenheim was unable to obtain 


1 Riban, Ann. Chim. Phys. [5] vi. 37. 

2 Ber. Deutsch. Chem. Gres. xvii. 2609. 

3 Wallach, Ann. Chem. Pharm. ccxxx. 249, 
4 Ibid. ecxxxix. 8 and 13. 

5 Ibid, lxvii. 367. 


462 AROMATIC COMPOUNDS, 


this compound of a constant boiling point, and Tilden found 
that the above reaction yields a mixture of a terpene with a 
compound, C,,H,,0, for which he retained the name terpinol.? 
It is also formed, together with terpilene, when dipentenylene 
chloride is heated with water. 

Wallach then showed that when the glycol is boiled with 
dilute sulphuric acid or phosphoric acid, the product consists, 
according to the conditions of the experiment, of dipentene, 
terpinolene, terpinene, cineol and the isomeric terpineol, this 
name being substituted for terpinol in order to correspond with 
borneol and cineol. It is formed by simple elimination of water 
from the glycol and is then partially converted into the other 
substances, as will be subsequently explained.‘ 

In order to prepare it, 25 grms. of the glycol are boiled 
with 50 cb. cms. of aqueous phosphoric acid. It is a very 
thick liquid, which has a pleasant smell, is optically in- 
active and boils at 215°—218°. According to Bouchardat and 
Voiry,? it 1s also formed when the glycol is heated with very 
dilute sulphuric acid and solidifies at —50° to crystals, 
melting at 30°—32°, by the aid of which crystallization may be 
induced at the ordinary temperature. This compound was 
probably obtained by Deville as a by-product of the preparation 
of terpine hydrate,’ and it also appears to occur in oil of 
cardamom from Ceylon (Hiletaria major). Dipentenylene ® 
chloride is formed when hydrochloric acid is passed into its 


ethereal solution : 
OH 


ee 
Nol 


OH Cl 
CHC + CIH = CF + H,0. 
Cl Cl 


C,,H,,.0H + ClH = C,H 


It is converted by hydriodic acid into the iodide and combines 
with water, in presence of dilute hydrochloric acid, to form the 
glycol. It also combines with bromine, but the compound 
formed does not admit of purification; an excess of bromine 
converts it into dipentene tetrabromide. On heating with 

1 Wallach, Ann. Chem. Pharm. cxxix. 155. 

2 Journ. Chem. Soc. xxxiii. 247 ; xxxv. 287. 

3 Tilden, Ber. Deutsch. Chem. Ges. xii. 1182 ; see also Flawitzky, ibid. 857. 

4 Ann. Chem. Pharm. ccxxx. 241; ecxxxix. 20. 


5 Compt. Rend. civ. 996. 6 Bouchardat and Lafont, zbid. cil. 1555. 
7 Ann. Chem. Pharm. xxi, 351. 8 Weber, zbid. cexxxviii. 98, 


DIPENTENE COMPOUNDS. 463 


sodium, hydrogen is evolved, and it decomposes when heated 
alone to 200° into water and dipentene, while it 1s partially con- 
verted by continued boiling with phosphoric acid into cineol 
and partially into terpinolene. Dilute sulphuric acid on the 
other hand produces chiefly terpinene. 

Dipentenyl phenylearbamate, C,,H,,0.CO.N H(C,H,), is formed 
by the combination of terpineol. with phenyl carbimide and 
crystallizes from alcohol in long needles, melting at 110°. 

Dipentenyl acetate, C,,H,,0.CO.CH, is obtained with difficulty 
when dipentene is heated with glacial acetic acid. It boils with 
decomposition at 220°, has an aromatic odour and is saponified 
by alcoholic potash with formation of terpineol (Bouchardat and 
Lafont). 

It follows from these facts that terpineol stands in the same re- 
lation to dipentenylene glycol as allyl alcohol to propylene glycol. 

Dipentene is readily formed from limonene; like this it com- 
bines with four atoms of bromine, but differs from it in being 
optically inactive, as is also cineol, which is believed by Briihl 
to contain no double linkings! These facts and the general 
behaviour of dipentene and its derivatives lead to the following 
constitutional formulae : 


Dipentene. Terpine. 
| 3 CH, 

C C.OH 
Ho7 NCH, HO” Nou, 
| | | | 
HC. CH HC, CH, 

G “OH 
| | 
C,H, C,H, 
Cineol. Terpineol, 
CH, ‘CH, 
| | 
C C 
H,0”|\cH, HOY \cH, 
O | | 
HC. | CH, H.C. CH, 
* G.OH 
| 
C,H, C;H, 


1 Briihl, Ber. Deutsch. Chem. Ges. xxi. 460. 


464 AROMATIC COMPOUNDS. 


The formation of dipentene from amylene, &c., is also easily 
explained : 


Amylene. Dipentene. 
CH, CH, 
| | 
CH C 
HC’ \cH, Hc” \cH, 
I Liahy. «I 
HC CH, HC. CH 
CH C 
| | 
CH CH 
va oN 
GH, OH, GH, OH, 


According to this formula it would contain the isopropyl 
group, but this is known to pass very readily into the normal 
group. 


SYLVESTRENE GROUP. 


2535 Stockholm tar and Archangel tar are obtained in the North 
of Europe by the dry distillation of fir wood (Pinus sylvestris 
and P. Ledbourii), and these are the source of both Swedish and 
Russian turpentine. The former was found by Atterberg to 
contain both australene and sylvestrene,! which are stated by 
Tilden to be also present in Russian turpentine,? while 
Wallach has observed the occurrence of dipentene in addition 
to these. 

Sylvestrene, C,,1,,, boils at 173°—175° (Atterberg) and smells 
like fresh fir wood; the chloride is formed by passing hydro- 
chloric acid into its ethereal solution and yields the pure hydro- 
carbon on heating with aniline or better with sodium acetate 
and glacial acetic acid. In the pure condition it boils at 
175°—178° and smells like oil of bergamot. The addition of 
a drop of concentrated sulphuric acid or fuming nitric acid 
to its solution in glacial acetic acid, or acetic anhydride, 
produces a splendid deep blue colouration. On heating to 250° 
it is partially polymerized, no dipentene or other terpene being 
formed, and it behaves in a similar manner towards boiling alcohol 


1 Ber. Deutsch. Chem. Ges. x. 1202. 2 Journ. Chem. Soc. xxxili. 80. 


TERPINOLENE GROUP. 465 











containing sulphuric acid. It is dextrorotatory and combines with 
the hydracids to form compounds from which it can be separated 
unaltered.! 

Sylvestrene tetrabromide, C,,H,,Br,, is obtained by the addition 
of bromine to a solution of the hydrocarbon in glacial acetic acid. 
It crystallizes in monosymmetric tablets, melting at 135°—136°. 
Its ethereal solution is dextrorotatory. 

Sylvestrenylene chloride, C,,H,Cl,. This compound, which is 
employed for the preparation of the pure hydrocarbon, is difficult 
to prepare from crude sylvestrene, since it is very soluble in the 
other hydrocarbons which are present. The separation must 
therefore be carried out at a low temperature, a mixture of the 
chloride with dipentenylene chloride being thus obtained, which 
is then separated by recrystallization from alcohol and ether. It 
crystallizes in long, hard, thin monosymmetric tablets, which 
melt at 72°, while a mixture with an equal amount of dipenteny- 
lene chloride fuses below 40°. 

Sylvestrenylene bromide, C,,H,,Br,, is prepared in a similar 
manner to the analogous dibromides; it resembles the chloride 
in every particular and melts at exactly the same temperature. 

Sylvestrenylene todide, C,,H,<1,, crystallizes from hot petroleum- 
spirit in small plates, which melt at 66°—67° and readily become 
coloured brown. 


TERPINOLENE GROUP. 


2536 Terpinolene C,,H,5. The formation of this hydrocarbon 
has already been discussed. It is best prepared by boiling 
dipentenyleneglycol with four times its weight of aqueous 
phosphoric acid of 20 per cent.? It is formed in considerable 
quantity when sulphuric acid acts on cineol, much terpinene 
being also formed, which is then probably converted into 
terpinolene.? It boils at 185°—190° and is optically inactive. 
Jt combines with hydrochloric and hydrobromic acids to form 
the corresponding dipentene derivatives, resembling limonene 


1 Wallach, Ann. Chem. Pharm. ccxxx. 240; ccxxxix, 24, 
2 Ibid. ecxxx. 262. 
3 Ibid, ecxxxix. 23. 


466 AROMATIC COMPOUNDS. 


in this respect and in forming a distinctive tetrabromide. 
Briihl ascribes to it the following constitution : 


CH, 
| 
C 


Ho” \cH, 


ae i 


| 
C,H, 


Terpinolene tetrabromide, C,,H,,Br,, crystallizes from ether in 
very lustrous monosymmetric tablets, which melt at 116° and 
‘change on preservation into a porcelain-like mass, which 
commences to melt below 100°, the liquid assuming a green 
colour and gas being evolved. Crystals of the bromide may be 
re-obtained by extracting the cooled mass with ether, but the 
greater portion of it is destroyed. 


TERPINENE GROUP. 


2537 Lerpinene, C,,H,,. The formation of this substance has 
frequently been referred to; it 1s formed by the action of 
sulphuric acid on pinene, dipentene, the glycol of the latter, 
cineol and phellandrene. In order to prepare it, 70 ccm. of 
concentrated sulphuric acid are added to two litres of oil of 
turpentine in portions of 5 ccm. at once, and the liquid well 
agitated, care being taken that the temperature does not rise 
so high that the vessel can no longer be conveniently handled. 
The mixture is then shaken up at repeated intervals for a 
whole day, neutralized with caustic soda and the product 
distilled with steam. Pure terpinene is obtained by fractional 
distillation of the product as a liquid, which boils at about 
180° and smells like lemons It occursalso in oil of cardamom 
from Ceylon (Hlettaria major)? is optically inactive and 
forms liquid addition-products with bromine and the hydracids ; 


1 Wallach, Ann. Chem. Pharm. ccxxx. 260; ccxxxix. 83. 
2 Weber, ibid. ccxxx. 98. 


TERPINENE GROUP. 467 


the hydrochloride, however, solidifies at a very low temperature. 
Dipentenylene chloride, which perhaps owes its formation to the 
presence of an impurity, is always formed together with the 
hydrochloride. It soon becomes resinous on exposure to air, and 
this change is also brought about to some extent by sulphuric 
acid, an isomeric terpene being also formed. It has probably 
the following constitution (Briihl) : 


CH,—CH, 
Oe NG On CH He 


\cH,—CH,/” 


Terpinene nitrosite, C,,H,,N,O.,, is formed by the action of 
sodium nitrite and dilute acetic acid on terpinene and crystal- 
lizes from alcohol in snow-white, monosymmetric prisms, 
melting at 155°. It dissolves without decomposition in strong 
acids but is decomposed by boiling with alkalis. 

Terpinene nitrolamine, C,oH,.N.,O, 1s obtained by the addition 
of ammonia to a hot alcoholic solution of the nitrosite : 


N.OH 


H 
= 2NH, as C.F 
mM hte 


CoE + NH,O.NO. 
O.NO 

It crystallizes from hot water in needles, which are readily 
soluble in alcohol and alkalis and melt at 116°—118°. Hydro- 
chloric acid precipitates crystals of C,,H,,.N,O.HCl from its 
ethereal solution. The amines react in a similar manner to 
ammonia, producing compounds most of which crystallize well. 

Terpinene nitrolmethylamine, C,,Hy;(NH.CH,)N.OH, crystal- 
lizes from alcohol in splendid prisms, which melt at 141° and 
also form a crystalline hydrochloride. 

Terpinene nitroldimethylamine, C,,H,,;N(CH;),N.OH, crystal- 
lizes less readily and melts at 160°—161°. 

Wallach has prepared several additional compounds.! 


PHELLANDRENE GROUP. 


2538 Phellandrene, C,)H,,. Cahours, who examined bitter 


1 Ann. Chem. Pharm. cexli. 315. 


468 AROMATIC COMPOUNDS. 





fennel oil,t found in it, together with anethol, “a compound 
apparently isomeric with oil of turpentine,” which is converted 
by nitrogen dioxide into a white crystalline substance. This 
latter, to be afterwards described, proved to be a compound 
of a terpene with nitrogen trioxide. Pesci submitted the 
ethereal oil of the seeds of the Water-Dropwort (Phellandrium 
aguaticum) to investigation and found in it the hydrocarbon 
phellandrene,? which was proved by Wallach to be identical with 
the terpene contained in bitter fennel oil? It has not yet been 
obtained in the pure state; it boils at about 171°—172° and is 
dextrorotatory. Hydrobromic acid acts upon its solution in 
glacial acetic acid with production of a heavy, oily bromine 
compound, which is converted into dipentene by heating with 
sodium acetate and acetic acid, whilst terpinene is formed when 
it is treated with hot alcoholic sulphuric acid. 
Briihl gives it the following constitution : 


AC 
CH,-cHY =- - SCH_CH=CH—CH,. 
Nols el 


Phellandrene nitrosonitrite, C,yH,,(NO)NO,. This compound, 
discovered by Cahours, was proved by Bunge not to be formed 
by the action of pure nitrogen dioxide on the hydrocarbon, but 
only in the presence of air. It is, therefore, more readily 
obtained by agitating the terpene with a solution of potassium 
nitrite and acetic acid.t It crystallizes in long needles, melting 
at 94° (Pesci) and is levorotatory. Its solution in chloroform 
does not decolorize bromine, so that it behaves as a saturated 
compound. Its constitution is different from that of terpinene- 
nitrosite, since it is not converted into a nitrol-base by the action 
of amines (Wallach). 

Phellandrene diamine, C,,H,,(NH,),, was obtained by Pesci 
by the reduction of the preceding compound as a liquid, boiling 
at 209°—214°. 

Nitrophellandrene, C,,H,,NO,, is formed by the action of 
ammonia on nitronitrosophellandrene and is a yellow, aromatic 


1 The bitter fennel (Fenowil amer) is a variety of the ordinary fennel (Ancthum 
Ffeniculuwm) which grows wild in Southern France, and whose seeds, which contain 
the oil, have an aromatic taste, resembling that of fennel, but taste bitter. 

2 Gaz. Chim. Ital. xvi. 225. 3 Ann. Chem. Pharm. ccxxxix. 40. 

4 Zeitschr. Chem. 1869, 579. 


PHELLANDRENE GROUP. 469 


smelling liquid, which is converted by reduction into amido- 
phellandrene, C,)H,,NH,, an oily liquid, which smells of coniine 
and forms crystalline salts. 


COMPOUNDS RELATED TO THE CAMPHORS. 


2539 Menthol or Menthyl alcohol, C,,H,,.OH, occurs, together 
with terpenes, in oil of peppermint, which is used in medicine, 
perfumery and for flavouring purposes. The peppermint (Mentha 
prperita) has been cultivated since the middle of last century 
at Mitcham in Surrey, near Wisbeach in Cambridgeshire, 
Market-Deeping in Lincolnshire, and Hitchin in Hertford- 
shire, and the oil extracted from the plants gréwn in those 
districts is still the most highly prized. Its culture has 
spread from England to other parts of Europe and to North 
America, whence considerable quantities of oil of peppermint 
are now obtained. Gaubius, in the year 1771, was the first to 
observe that the oil extracted from the plants near Utrecht 
deposited crystals of Camphora Europaea Menthe Piperitides 
The Japanese and Chinese oils contain this substance in much 
larger quantities, and frequently occur in the form of a crystal- 
line mass saturated with liquid hydrocarbons; these oils are 
not derived from the European peppermint, but from other 
species of Mentha (JZ. arvensis var. piperascens et glabrata). 

This peppermint-camphor was mistaken for ordinary camphor 
until Dumas? and Blanchet and Sell® determined its composition, 
and Walter‘ fixed its molecular formula by a determination of 
its vapour density, which was found to be 5°62. It was recognized 
as an alcohol by Oppenheim.® 

Menthol crystallizes in prisms, which have a strong smell of 
peppermint and melt at 42°° It boils at 212°, is levorotatory 
and decomposes on heating with phosphorus pentachloride or 
zinc chloride into water and menthene, C,,H,,, a dextrorotatory 
liquid, which smells like cymene, boils at 167° and combines 
with bromine. The addition product, C,,H,,Br, thus formed is 
converted into cymene by heating and distilling the product 
with sodium (Beckett and Wright). 


l Flickiger, Pharmakognosie, 686. 

2 Ann. Chem. Pharm, vi. 252. 3 Ibid. vi. 293. 

4 Ibid, xxxii. 288. 5 Ibid. exx. 850; cxxx. 176. 
6 Beckett and Wright, Jowrn. Chem. Soc. 1876, i. 1. 


470 AROMATIC COMPOUNDS. 





Menthol is employed both for internal and external application 
in medicine, and is sold in pencils as aremedy for neuralgia. The 
Chinese peppermint oil serves the same purpose and has long 
been employed in this way in China and Japan, where it is sold 
in small bottles under the name of Po-ho-yo. 

Sodium menthylate, C,)»H,,0Na, forms a vitreous mass, which 
is readily soluble in alcohol. 

Menthyl chloride, C,)H,,Cl, was obtained by Walter by the 
action of phosphorus pentachloride on menthol, while Oppenheim 
prepared it by heating with hydrochloric acid. It is also formed 
by the combination of menthene with hydrochloric acid and 
is a liquid, which has a pleasant odour resembling that of 
mace and a refreshing taste, and boils with decomposition 
at 204°. 

Menthyl bromide, C,,H,)Br, is formed by the action of phos- 
phorus bromide on menthol, and is a liquid which decomposes 
on boiling. 

Menthyl rodide, C,,H, 1, forms a heavy, faintly yellow liquid, 
which, like the bromide, decomposes when heated with alcoholic 
potassium sulphide or ammonia, with formation of menthene. 

Menthyl carbonate, (C,)H,,),CO., is obtained, together with the 
following compound, when cyanogen is passed into a solution of 
sodium menthylate in toluene and the product treated with water. 
It is a crystalline mass which melts at 105°. 

Menthyl carbamate, C,,H,,0.CO.N H., crystallizes from alcohol 
in thin prisms, which melt at 165° and readily sublime.t 

Menthyl phenylearbamate, C,),H,,0.CO.NH(C,H,), 1s formed 
by the combination of menthol with phenylcarbimide, and 
crystallizes from alcohol in silky needles, melting at 111°? 

Menthyl acetate, C,,H,,0.C,H,0, was prepared by Oppenheim 
by heating menthol to 150° with glacial acetic acid or acetic 
anhydride as a thick, strongly refractive liquid, which is 
leevorotatory and boils at 222°—224°. 

Menthone, C,,H,.0, is formed by heating menthol with sul- 
phuric acid and potassium bichromate.*? It is a mobile liquid, 
which smells of peppermint and boils at 206°. When its 
solution in petroleum is heated with sodium and a current of 
carbon dioxide passed through the mixture, the product yields 
menthol on decomposition with water. The latter substance 


1 Arth, Compt. Rend. xciv. 872. 
2 Leuckart, Ber. Deutsch. Chem. Ges. xx. 114. 
3 Moriya, Journ. Chem. Soc. 1881, i. 77. 


ISOMERIDES OF BORNEOL. 471 


therefore bears the same relation to menthone as borneol to 
camphor :! 


Menthol. Menthone. 

CH, OH, 

| 

CH CH 
H,C” \CH.OH H,C” SCO 
HC. OH, HC. OH, 

CH CH 

| | 

C3H, C,H, 


The molecular refractions of the compounds also agree with 
these formule.” 


ISOMERIDES OF BORNEOL. 


2540 The genus Andropogon is distinguished from other 
grasses by the fact that many of its species contain an essen- 
tial oil, which is employed in India as a perfume and as a 
medicine and is also valued in Europe for its fragrance. 

Indian Melissa orl or Lemon-grass oil is derived from A. citratus, 
a lofty grass, which is cultivated in Singapore and Ceylon. It 
occurs in commerce under the name of oi of verbena, since 
its odour resembles that of the fragrant verbena (Lippia 
citriodora). 

Citronella oil is extracted in the same districts from <A. 
nardus, and smells like roses and lemons. It contains citronellol, 
C,,H,,0, which boils at about 210° and yields a dibromide, which 
decomposes on heating into water, hydrobromic acid and 
cymene.* 

Indian oil of geraniwm is contained in A. Schoenanthus, a. 
graceful grass indigenous to Northern and Central India. It is 
also called Rusa oil and oil of ginger grass, and is exported in 
considerable quantities from Bombay to Europe, chiefly to 

1 Atkinson and Yoshida, Journ. Chem. Soc. 1882, i. 49. 


2 Briihl, Ber. Deutsch. Chem. Ges. xxi. 457. 
3 Gladstone, Journ. Chem. Soc. 1872, 7; Wright, ibid. 1874, 317. 


296 


472 AROMATIC COMPOUNDS. 





Constantinople and Kazalanik, where it is used to adulterate 
attar of roses. In order to fit it for this purpose, it is exposed 
to the sun in flat basins, under which conditions it loses its 
somewhat acrid smell, which then becomes very similar to attar 
of roses! It contains valerianic acid and geraniol, which will 
subsequently be further investigated. 

Turkish oil of geranium is derived from A. packnodes, indi- 
genous to India, Persia and Arabia. 

German oil of geranium, as well as the French Olewm palme 
rose, is obtained by the distillation of Pelargoniwm Radula, and 
contains geraniol and pelargonic acid? (Vol. III. Part I. p. 660). 
The oil prepared in Algiers from P. rosewm et odoratissimum 
is very similar to these (Gintl). 

Geraniol, C,,H,,,OH, can be separated from Indian oil of 
geranium as a colourless, strongly refractive liquid, which is 
optically inactive, boils at 232°—233°, and has a very pleasant 
smell of roses. It is oxidized by potassium permanganate to 
valerianic acid and is converted by heating with nitric acid into 
oxalic acid, nitrobenzene and other substances. 

Geranyl ether, (C,)H,,),0, 1s formed when the chloride is 
heated with water or to 100°—200° with geraniol, and is a 
liquid, which has a characteristic smell of peppermint and boils 
at 187°—190°. 

Geranyl chloride, C,,H,,Cl, is obtained by the action of hydro- 
chloric acid on geraniol, and is an oily liquid, which has an odour 
resembling that of camphor and decomposes on heating. Geranyl 
bromide and todide may be prepared from this by the action of 
potassium bromide and iodide ; they are heavy, oily liquids, which 
decompose even more readily than the chloride. The valerate, 
benzoate and cinnamate, have all been prepared and are pleasant 
smelling liquids, which cannot be distilled without decomposition. 

Geranyl sulphide, (C,)H,,).5, 1s formed by the action of the 
chloride on an alcoholic solution of potassium sulphide. Itisa 
yellowish, very unpleasant smelling liquid.? 

Linaloéol, C,,H,,0. Among the costly spices mentioned in 
the Old Testament is aloes, by which is to be understood not 
the sap of the aloe plant but the fragrant wood of Aquilaria 
Agallocha, a large forest-tree, a native of the Malay Peninsula 
and the neighbouring islands, 


1 Pharmacographia, 725 ; Fliickiger, Pharmakognosie, 157. 
2 Gintl,, Jahresber. Chem. 1879, 941. 
3 Jacobsen, Ann. Chem. Pharm. clvii. 282. 


ISOMERIDES OF BORNEOL. 473 


Lignum aloes was found up to the end of last century among 
our drugs, but is now exclusively employed in Eastern Asia as a 
perfume. Since the seventeenth century, a fragrant wood has 
been imported from Mexico to which the above name has been 
given, while linaloes wood now comes from Cayenne and is 
derived from Jcica altissima. The linaloéol, contained in 
it, is a liquid, smelling of roses and lemons and boiling at 
198°, It is converted by hydrochloric acid into a liquid chloride, 
C,)H,gCl,, which smells like camphor and on distillation with 
lime yields a terpene, having a characteristic, faintly aromatic 
odour and boiling at 168°—172° 

Coriandrol, C,)H,,0, is the chief constituent of oil of corian- 
der (Coriandrum sativum) and is a liquid, which volatilizes 
without decomposition only below 150°. If it be gradually 
heated, it commences to boil at this temperature, but the boiling- 
point rises, water being gradually eliminated and coriandryl 
ether, (C,,H,,),0, formed. This substance boils at 168°—170° 
and is accompanied by a polymeric condensation product, boiling 
at 190°—196°. When coriandrol is heated to 200° or distilled 
over phosphorus pentoxide, a terpene is obtained, together with 
polyterpenes. Coriander oil detonates very violently with iodine ; 
the first product of the action of potassium permanganate upon 
it is an oily liquid, boiling at 185°—186°, which is isomeric with 
camphor and is converted into carbon dioxide, acetic acid and 
dimethylsuccinic acid by further oxidation. 

Coriandryl chloride, C,,H,,Cl, is formed by passing hydro- 
chlorie acid into coriandrol as a yellowish liquid, which smells 
like camphor and, decomposes on heating. 

Coriandry! iodide, C,)H,,I, is obtained in a similar manner, 
and when freshly prepared is a yellowish oil, which explodes on 
heating even below 100°. Iodine rapidly separates out when the 
compound is preserved and this decomposed substance yields 
cymene on heating. 

Coriandryl acetate, C,,H,,.C,H,0,, is formed when coriandrol 
is heated with acetic anhydride and is a liquid, which boils at 
228°—236° with decomposition.” 

Tanacetyl alcohol, C,,H,,O, occurs in oil of tansy (Tanacetum 
vulgare), boils at 203°—205° and yields a smail amount of 
ordinary camphor on oxidation with chromic acid. It is accom- 
panied by tanacetol, C,,H,,O, a liquid boiling at 195°—196°, the 


1 Morin, Compt. Rend. xcii. 998; xciv. 733. 
2 Grosser, Ber. Deutsch. Chem. Ges. xiv. 2485. 


A74 AROMATIC COMPOUNDS. 


smell of which faintly resembles that of the plant. It is con- 
verted into cymene by heat and is oxidized to camphoric acid 
by nitric acid. Acid sodium sulphite combines with it to 
form a crystalline compound, it reduces ammoniacal silver solu- 
tion and yields tanacetyl alcohol on reduction. It therefore 
appears to be the aldehyde of the latter, which probably has the 
following constitution : 

Avie 

( 


HO” | \CH,.OH 


| 
HC, | (CH, 


NZ 


C 
| 
C,H, 


ISOMERIDES AND HOMOLOGUES OF CAMPHOR. 


2541 Alantol, C,,H,,0, occurs in the root of elecampane 
(Inula Heleniwm) and is a liquid, which smells like peppermint 
and boils at about 200° and is levorotatory.? 

Salviol, C,,H,,0, is found, together with camphor and tere- 
bentene, in oil of sage (Salvia officinalis), and is a liquid, boiling 
at 197°—203°3 

Myristicol, C,,H,,0, occurs, together with a terpene and 
cymene in the ethereal oil of nutmeg; it boils at 212°—218° 
and is polymerized by repeated distillation.* 

These three compounds are converted into cymene by distil- 
lation with phosphorus chloride. 

Pulegiol, C,)Hy,0, forms the chief constituent of the oil of 
Pulegium micranthum, a plant which grows on the steppes of 
South Russia; it smells like peppermint, boils at 227° and 
absorbs hydrochloric acid, without forming a solid compound.® 


1 Bruylants, Ber. Deutsch. Chem. Ges. xi. 449. 

2 Kallen, dbid. ix. 154; Marpmann, Arch. Pharm. [8] xxv. 826. 
3 Muir and Sugiura, Jowrn. Chem. Soc. 1878, i. 292, 

4 Wright, zbid. 1873, 549 and 686. 

5 Butlerow, Jahresber. Chem. 1854, 594. 


ISOMERIDES OF CAMPHOR. 475 


Oil of chamomile. The flowers of the false or wild chamomile 
(Matricaria chamomilla) were employed medicinally at an early 
date. According to Pliny and Dioscorides, the name Xaya/unrov 
relates to the odour, which is not unlike that of the apple 
(yapat, on the ground, uo, apple), the plant which is found 
in Greece having an especially fine odour. Joachim Camerarius 
mentions in his Hortus medicus et philosophicus, 1588, that a 
blue oil is obtained by the distillation of chamomile with water, 
and recommends it as a remedy for the colic! This substance, 
which is still employed in medicine, is a deep-blue, viscid oil, 
which almost takes the consistency of butter at a low tempera- 
ture and has a strong smell of chamomile and a warm aromatic 
taste. 

It contains caprinic acid, C,,H,,O.2, chamomillol, C,>H,,O, which 
is colourless, smells strongly of chamomile and boils at 150°— 
163° and trichamomillol, C,,H,,0;- The last is the deep-blue, 
viscid portion, has a very mild smell, boils at 270°—300° and 
forms a deep indigo-blue vapour. It also occurs, together with 
_ absinthol, C,,H,,0, boiling at 195°, in the ethereal oil of worm- 
wood (Artemesia absinthiwm),? in the oil of Pilchurim beans # 
and in the oil obtained by the dry distillation of galbanum. 
This also contains a triterpene, C,)H,,, which is formed when 
trichamomillol is heated with sodium or potassium. It is colour- 
less, boils at 255° and has a mild taste and a faint herbaceous 
odour.> © 

Matico camphor, C,,H,)0, is a homologue of camphor and 
occurs in the leaves of the narrow-leaved pepper (Piper angusti- 
folium), which is a native of South America and is employed to 
staunch the bleeding of small wounds, such as those caused by 
blood leeches. This property is said to have been discovered 
by the Spanish soldier Matico, and the Matico leaves are there- 
fore also known as Yerba del soldato. They contain an ethereal 
oul, from which the camphor separates in hexagonal crystals at a 
low temperature. The compound after purification by re- 
crystallization from alcohol has neither smell nor taste, melts at 
94° and takes up a rotatory motion when thrown on to water.’ 

1 Fliickiger, Pharmakognosie, 787. 

2 Kachler, Ber. Deutsch. Chem. Ges. iv. 36. 

3 Beilstein and Kupffer, Ann. Chem. Pharm. clxx. 290. 

4 Miiller, Jahresber. Chem. 1853, 514. 


5 Mossmer, Ann. Chem. Pharm. cxix. 257. 6 Pharmacographia, 589. 
7 Kiigler, Ber. Deutsch. Chem. Ges. xvi. 2841. 


476 AROMATIC COMPOUNDS. 


SESQUITERPENES, (C,,H,,, AND SESQUI- 
CAMPHORS, (,,H,,0. 


2542 Cubebene was first detected as a constituent of oil of 
cubebs (Piper Cubeba) It was also found by Wallach in oil of 
galbanum, oil of patchouli (Pogostemon patchoult), oil of savin 
(Juniperous sabina), and in large quantity in the so-called Ole- 
um cadinwm, the tar of which is obtained in Southern France 
by the distillation of the wood of a species of juniper, 
especially J. Oxycedrus,? and is a thick, black-brown liquid. In 
order to separate cubebene from it, the volatile portions are dis- 
tilled with steam, treated with alkali to remove phenols, dried 
over caustic potash and fractionated. The portion boiling between 
260°—280° is then diluted with two volumes of ether, saturated 
with hydrochloric acid, allowed to stand for a few days and the 
ether then evaporated or distilled off. The chloride, C,,H,,CL,, 
crystallizes from the residue and is drained off, washed with a 
little cold alcohol and recrystallized from hot acetic ether, It is 
then decomposed by heating with aniline or by boiling with 
glacial acetic acid and sodium acetate.? 

Cubebene boils at 274°—275° and has a sp. gr. 0°921 at 16°; 
it is levorotatory and readily changes into a resin on exposure 
to the air. 

If it be dissolved in chloroform or glacial acetic acid and then 
shaken up with a few drops of sulphuric acid, the liquid becomes 
coloured green, which soon passes into blue and is converted into 
red by heating. This remarkable reaction is best shown by the 
hydrocarbon after it has become partially converted into a 
resin.‘ | 

Cubebenylene chloride, C,,H,,Cl,, is readily obtained by mixing 
cubebene with a few volumes of glacial acetic acid, and then 
agitating it with fuming hydrochloric acid. It crystallizes from 
ether in hemihedral rhombic prisms, the faces of which are 
striated and which show a striking resemblance to those of 


1 E. Schmidt, Arch. Pharm. [2] exli. 1; Ber. Deutsch. Chem. Ges. x. 188. 

2 Oglialoro, ibid. viii. 1357. 

3 Wallach, Ann. Chem. Pharm. ccexxxviii. 78. 

4 Ifa few drops of crude oil of cubebs be shaken with twenty drops of carbon 
disulphide and with one drop of a cooled mixture of equal parts of concentrated sul- 
phuric and nitric acids, the liquid becomes coloured greenish and then blue 
(Flickiger, Pharmakognosie, 874). 


SESQUITERPENES AND SESQUICAMPHORS. 477 


limonene tetrabromide, but are levorotatory. It melts at 
117°—118°. 

Cubebenylene bromide, C,;H,,Br,, forms snow white needles, 
resembling those of the chloride, which melt at 124°—125° and 
are decomposed by continued boiling with alcohol. 

Cubebenylene todide, C,;H,,I,, crystallizes from petroleum spirit 
in white woolly needles, which melt at 105°—106° with de- 
composition and are also rapidly decomposed by boiling with 
alcohol. Cubebene itself has probably the following con- 
stitution. 


CH, 


CH| CH 


ONIZ\N 
HC: 102 CH 


bed: Pee 
HC CH CH 
VION RGN 
CH, CH, GH, CH, 


Camphor of cubebs, C,;H,,0, sometimes crystallizes from the 
oil of old, long preserved samples of cubebene, and forms large, 
odourless, rhombic prisms or pyramids, which melt at 67° and 
are decomposed into water and cubebene when they are heated 
to 250° or allowed to remain in contact with sulphuric 
acid. 

Commene, C,,H,,, is obtained by the distillation of conima 
resin (Jcica heptaphylla), which is used as incense in British 
Guiana. It is a liquid, which has an extremely pleasant 
aromatic odour and boils at 264°.1 

Cedar camphor, C,,H,,O, occurs, accompanied by cedrene, 
C,;H.,, or C,;H,.,? in the ethereal oil of the Virginian cedar 
(Juniperus virginiana), and crystallizes in silky needles, which 
have a characteristic spicy odour. It melts at 74°, boils at 282°, 
and decomposes on heating with phosphorus pentoxide into 
water and a sesquiterpene, which boils at 237°, has a character- 
istic aromatic odour, quite distinct from that of cedar camphor, 
and a burning taste like that of pepper.® 

Ledum camphor, C,;H,,O, is found, together with a sesquiter- 
pene in Labrador Tea (Ledwm palustre), and crystallizes in 

1 Stenhouse and Groves, Jowrn. Chem. Soc. 1876, i. 175. 


2 Chapoteaut, Bull. Soc. Chim. xxxvii. 303, 
3 Walter, Ann. Chem. Pharm, xxxix. 249 ; xlviii. 35. 


478 AROMATIC COMPOUNDS. 


almost odourless prisms, which melt at 104°—105° and readily 
sublime in needles. When it is heated to 150° with acetic an- 
hydride, it is decomposed into water and a sesquiterpene, which 
boils at 264°. 

Patchouli camphor, C,;H,.0, is contained in oil of patchouli, 
which is obtained by the aqueous distillation of the leaves and 
young shoots of Pogostemon patchouli, a labiate plant indigenous 
to India, and is said to produce nervous excitement and loss 
of appetite when employed as a perfume. The camphor 
crystallizes in hexagonal prisms, melts at 59°, boils at 296°, and 
is decomposed by the action of hydrochloric acid or acetic 
anhydride into water and patchoulene, C,,H.,, which boils at 
252°—255°2 

Santalol, C,,H,,O0. The fragrant white or yellow sandalwood 
(lignum Santali album) is derived from the Indian Santalwm 
album and other species of santalum, which grow in various 
districts of Australia. It was highly prized at an earlydate in India 
and was formerly kept in store by druggists. At the present 
time it is employed in India and especially in China as incense, 
and also for ornaments. It contains 2—5 per cent. of an 
ethereal oil, which was likewise extracted at an early period and 
used as a perfume. This oil contains a substance named 
santalal, C,,H,,O, boiling at 300°, together with a smaller 
amount of santalol, which boils at 310° and is converted by 
distillation with phosphorus pentoxide into santalene, C,,H,,, 
boiling at 260°; santalal, on the other hand, when subjected to 
similar treatment, yields a hydrocarbon C,,H,., which is probably 
identical with cedrene.? 

Santalyl acetate, C,,H,;.C,H,0,, is prepared by heating santalol 
to 150° with glacial acetic acid, and is a liquid which boils at 298° 
and has a fruity odour. 

Volatile constituents of Paracota bark. This substance, which 
has already been mentioned (Part IV. p. 355), contains an ethereal 
oil, which may be obtained by distillation with superheated steam 
or by extraction with ether. It is a mobile liquid, possessing a 
very agreeable odour and contains the following compounds : 

a-Paracotene, C,,H,., 1s a strongly refractive liquid, which has 
a penetrating odour, resembling those of the oils of bitter- 


1 Trapp, Ber. Deutsch. Chem. Ges. viii. 542 ; Hjelt and Collan, zbid. xv. 2500; 
Rizza, tbid. xvi. 2311; xx. Ref. 562. 

2 Montgolfier, Bull. Soc. Chim. xxviii. 414. 

3 Chapoteaut, ibid, xxxvii. 303. 


THE DITERPENES. 479 





almonds and turpentine, boils at 160°, is dextrorotatory and does 
not combine with hydrochloric acid. 

B-Paracotene, C,,H,., has a faint but pleasant odour, boils at 
170°—172°, is feebly levorotatory and also forms no compound 
with hydrochloric acid. 

a-Paracotol, C,.H,,O, is a tolerably refractive liquid, which boils 
at 220°—222°, has a faint odour and is levorotatory. 

B-Paracotol, C,gH,.O,, boils at 236°, has a faint aromatic 
odour and is strongly refractive and levorotatory. 

y-Paracotol, C,,H,,0,, boils at 240°—242° and has a faint, not 
unpleasant odour and a very feeble levorotation.! 


THE DITERPENES, C,,H,. 


2543 Copawaene is a constituent of balsam of copaiba, which is 
itself a mixture of resins and hydrocarbons.” That prepared from 
Para-balsam is a liquid, whose odour resembles that of the 
balsam ; it boils at 252°—256°, and is converted by oxidation into 
acetic acid and asymmetric dimethylsuccinic acid,’ (CH,),C 
(CO,H)CH,.CO,H. Brix discovered a diterpene in maracaibo 
balsam, which boils between 250°—260°, and on oxidation with 
chromic acid gave a small amount of terephthalic acid, in 
addition to acetic acid. The dry oil may be rectified over 
sodium without undergoing any change, whereas in the presence 
of moisture it is converted into a deep blue liquid, which was 
termed the hydrate of oil of copaiba, C,,)H,.0=3C,,H,,+H,O, 
by Brix. It boils between 252°—260° and is reconverted into 
the colourless oil by distillation with phosphorus pentoxide.‘ 

Colophene is formed, together with other products which have 
already: been described, by the action of sulphuric acid or 
phosphorus pentoxide on oil of turpentine, and also by the 


1 Jobst and Hesse, Ann. Chem. Pharm. excix. 75. 

2 Copaiba balsam is the resinous sap of several species of Copaifera, which are 
indigenous to South America ; it is first mentioned by a Portuguese monk, who 
lived in Brazil between the years 1570-1600. He states that a clear oil, highly 
prized for its medicinal qualities, was obtained by incisions in the bark of the 
Cupayba, a forest tree. It was frequently described soon after this date, and is 
found mentioned in the Amsterdam Pharmacopeeia as Balsam. copae. yvae. The 
different varieties distinguished in trade are the Para Balsam, from the basin of the 
Amazon, and the Maracaibo Balsam, which comes from the Orinoco and Venezuela. 

3 Levy and Englander, Ann. Chem. Pharm. cexlii. 189. 

4 Monatsh. Chem. ii. 507. 


480 AROMATIC COMPOUNDS. 


distillation of colophonium,! and is an oily, viscid liquid, which 
boils at 318°—320°? 

Heveene is obtained, together with isoprene and dipentene by 
the dry distillation of caoutchouc or gutta-percha, and is a faint 
smelling, sharp tasting liquid, which boils at about 315°3 

Gurjunol, C,,H,.(OH),, is a constituent of gurjun balsam or 
wood-oil, which is extracted from various species of Diptero- 
carpus in Eastern India and the Malay Islands. It is very similar 
to balsam of copaiba and is used in place of this, although 
it finds its chief application as a varnish. Gurjunol is readily 
soluble in alcohol and is precipitated from this solution in long, 
silky needles, which melt at 126°—129°. When it is boiled with 
sodium acetate and acetic anhydride, the acetic ether, C,H, 
(C,H,0O,),, is formed ; it crystallizes from alcohol in small needles, 
melting at 74°—75°4 


ACIDS OF THE FORMULA (C,H,,0,. 


2544 Pimaric acid is the chief constituent of the resin of 
Pinus maritima, which is called galipot. It was discovered 
by Laurent® and carefully investigated by Sievert® and 
Duvernoy.’ Versterberg was the first to show that this is not a 
homogeneous substance. He detected in it at least three 
different acids, two of which he investigated more thoroughly, 
although they had already been examined by Cailliot, who had 
not, however, succeeded in obtaining them in the pure state. In 
order to extract them, finely divided galipot is repeatedly treated 
with small quantities of alcohol of 70 per cent. and finally once 
with 80 per cent. alcohol, the residual mass being then dissolved 
in hot 3 per cent. caustic soda solution. The sodium salts of 
dextropimaric and levopimaric acids separate out after a few 
days and are recrystallized from hot water and decomposed 
with dilute hydrochloric acid, the precipitated acids being 
purified by repeated crystallization from alcohol or glacial 
acetic acid. 

1 Deville, Ann. Chem. Pharm. xxxvii. 193 ; Ixxi. 150. 

2 Riban, Ann. Chim. Phys. [5] vi. 40. . 

3 A. Bouchardat, dunn. Chem. Pharm. xxvii. 80. i 

* Brix, Monatsh. Chem. ii. 515. 5 Ann. Chem. Phys. Ixxii. 384. 


8 Jahresber. Chem. 1859, 508. 7 Ann. Chem. Pharm. exlviii. 148. 
8 Ber. Deutsch. Chem. Gies. xviii. 8331 ; xix. 2167. 


PIMARIC ACIDS. 481 


Dextropimarie acid is insoluble in water but dissolves slightly 
in cold and readily in hot alcohol and glacial acetic acid, from 
which it crystallizes in large, rectangular plates, while it is 
deposited in tablets when its ethereal solution is evaporated. 
It is dextrorotatory, melts at 210°—211°, solidifies to a 
crystalline mass and may be distilled under diminished 
pressure. The long continued action of sodium amalgam on 
its alcoholic solution is without effect. When hydrochloric acid 
gas is passed into its uncooled ethereal solition, it is converted 
into an isomeric form, which probably consists of sylvie acid. 
If dextropimaric acid be heated to 250° with concentrated 
hydriodic acid and amorphous phosphorus, the hydrocarbon, 
C,H,,, is formed as a viscous liquid, boiling between 320°—330°. 
The dihydrocolophene, which is obtained by the action of sodium 
on pinyl chloride and is a liquid resembling colophene and 
boiling at 321°, is probably identical with this substance.’ 

Potassium dextropimarate, C,,H,,KO,, solidifies, when its hot 
solution is cooled, to a soap-like mass, which consists of very fine, 
pliable needles. 

Sodium deatropimarate, C,,H,,NaO, + 5H,O, crystallizes from 
water in nacreous plates and from alcohol in fine needles. It is 
precipitated from its solution by common salt or an excess of 
alkali. 

Ammonium dextropimarate separates out in fine needles, when 
the ethereal solution of the acid isshaken up with ammonia, this 
being a very characteristic property. 

Silver dextropimarate, C,,H,,AgO,, is an amorphous 
precipitate, which soon changes to a heavy powder consisting 
of small prisms. 

The calcium, barium and lead salts are all precipitates con- 
sisting of needle-shaped crystals. 

Hithyl dextropimarate, C,,H9(C,H,)O,, is formed by the action 
of ethyl iodide on the silver salt. It crystallizes from alcohol 
in long, flat prisms, which melt at 52°. 

Dectropna yl chloride, C.,H, OCI, is prepared by treating 
the acid with phosphorus pentachloride, and forms small prisms, 
melting at 64°—66°. 

Levopimarie acid is more readily soluble in alcohol than 
dextropimaric acid, and crystallizes in rhombic pyramids, which 
melt at 140°—150°. Its levorotation is four times as great as the 


1 Montgolfier, Ann. Chim. Phys. [5] xix. 150. 


482 ~ AROMATIC COMPOUNDS. 


dextrorotation of the isomeric acid; its salts resemble those of 
dextropimaric acid. 

2545 Sylvic acid is, according to Unverdorben, the chief 
constituent of colophony.? It has been investigated by 
Trommsdorff Rose,* and Sievert,’ and is obtained by treating 
colophony with cold alcohol, and crystallizing the residue from 
hot alcohol, to which a little sulphuric acid should be added. 
Maly advanced the view that colophony does not contain 
sylvic acid as such. He assumed that the former substance is 
the anhydride of abretic acid, C,,H,,0,, which is converted into 
the free acid by treatment with alcohol, and is then further 
changed into sylvic acid by the action of mineral acids.° 
Further investigations have however shown that abietic acid 
and sylvic acid only differ in degree of purity, and their formula 
has not yet been definitely ascertained. Liebermann and 
Haller, who analyzed purified sylvic acid, obtained numbers 
which agree with the formula of abietic acid;’ this substance 
softens at 145° and melts at 162°. Valente, on the other hand, 
states that when colophony in powder is extracted with strong 
alcohol, water added until the solution becomes turbid, and this 
turbidity removed by the addition of a further quantity of 
alcohol, a crystalline mass rendered impure by resinous matter 
is deposited after a few days, and this may be obtained by a re- 
petition of the process in prisms, the melting-point of which is 
about 160°, but is not constant; a series of analyses of products 
obtained in this way gave numbers, some of which agree with 
the formula C,,H,,O, and some with C,,H,,0,. If the crystals 
be treated for some hours on the water-bath with dilute sodium 
carbonate solution, the liquid filtered and dilute sulphuric acid 
added, pure sylvic acid, C,,H,,O,, is obtained; this substance 
crystallizes from alcohol in prisms and melts at 146°—148°. 

It appears from the above that sylvic acid, like pimaric acid, is 
a mixture, this supposition beimg confirmed by the fact that 
while Valente’s acid is dextrorotatory, the substance prepared by 
Liebermann is levorotatory. 

Colophony appears to have received its name from the 
Tonian town Kolophon; Dioscorides mentions xododwvia, 


1 Vesterberg, Ber. Deutsch. Chem. Ges. xx. 3248. 

2 Pogg. Ann. vii. 311; viii. 40 and 407; xi. 28, 230 and 398; xiv. 116; xvii. 
186. 3 Ann. Chem. Pharm. xiii. 109. 
4 Pogg. Ann. xxxili. 42 ; liii. 874. 5 Jahresber. Chem. 1859, 568. 

6 Ibid. 1861, 389; Ann. Chem. Pharm. cxxix. 94; cxxxii. 249; clxi. 115. 
See also Emmerling, Ber. Deutsch. Chem. Ges. xii. 1441; Kelbe, <dd. xiii. 888. 
7 Ibid, xvii. 1884 ; xviii. 2165. 8 Ibid. xviii. Ref. 190. 


SYLVIC AND GUAICIC ACIDS. 483 


and Pia graeca or Colophonia was used by the German apothe- 
caries of the fifteenth century. It is obtained on the large scale, 
together with oil of turpentine, by the distillation of turpentine 
especially in the United States, where this great industry was 
commenced in the last century.! 

Colophony forms a yellow transparent or darker coloured 
translucent mass, which has a conchoidal fracture, softens 
at 80° and melts between 90° and 100°. When heated for some 
time with nitric acid, it yields terebic acid, isophthalic acid, 
and trimellithic acid. 

It is employed in the manufacture of resin soap (Vol. III. Part 
I. p. 693), which consists of the sodium salt of sylvic acid and the 
substances which occur with it. A concentrated solution of this 
dissolves considerable quantities of colophony, producing resin 
glue, which forms with water a milky fluid, employed for sizing 
paper. 

On dry distillation colophony yields the essence of resin or 
resin oil, which has already been frequently referred to and is 
used as a lubricant, &c. 

Copaivic acid is the chief constituent of copaiba resin, which 
remains behind when the balsam is distilled with water, and 
may also be readily obtained from the latter by agitating it 
continuously with ammonium carbonate solution and then pre- 
cipitating with acetic acid. It forms large crystals, which are 
readily soluble in alcohol.? 

Silver copaivate, C,,H,,AgO,, is obtained as a crystalline pre- 
cipitate by the addition of an ammoniacal silver solution to the 
alcoholic solution of the acid. 

Metacopaivic acid, C,,H;,0,, is contained in maracaibo balsam, 
and crystallizes from alcohol in plates which melt at 205°— 
206°, and were until recently mistaken for gurjunol (p. 480). 


GUAIACIC ACID, C,,H,,0,. 


2546 Soon after the discovery of St. Domingo, the Spaniards 
observed that the natives employed the wood of Hujacum 


1 Fliickiger, Pharmakognosie, 93. 

2 Schweizer, Pogg. Ann. xvii. 488 ; xxi. 172; Rose, ibid. xxxiii. 35 ; liii. 372 ; 
Hess, ibid. xlvi. 324; Fliickiger, Jahresber. Chem. 1867, 727. 

3 Strauss, Ann. Chem. Pharm. exlviii. 153. 


484 AROMATIC COMPOUNDS. 





(Guaiacum officinale) as a remedy for skin diseases ; this tree is 
also found indigenous in all the West Indian Islands, and on the 
south coast of South America. The wood aroused great interest 
in Europe since it was recommended as a remedy for syphilis 
(Morbus gallicus), which was at that period very prevalent. 
It was especially praised by Ulrich v. Hutten, who suffered 
from this disease, in his treatise “ Ulricht de Hutten Eq. De 
Guaict medicina et morbo gallico liber unus. Monguntiae in 
aedibus Joannis Scheffer, mense Aprili, wnterregni vero quarto 
Anno 1519,” which was translated in 1533 by Thomas Paynel, 
canon of Merton Abbey, and published in London 1536.1 In the 
Island of St. Domingo it is collected from the stems of the tree 
as a natural exudation or as the result of incisions made in the 
bark. In the Island of Gonave near Port-au-Prince another 
method is used. A log is supported in a horizontal position 
above the ground by two bars and each end of the log set on 
fire, the melted resin running from a large incision, which has 
previously been made in the middle. 

Guaiacum resin is a brittle, dark green to brownish-black 
mass, which readily dissolves in alcohol. Oxidising agents 
such as ferric chloride or ozone, colour the solution a fine 
blue. When submitted to dry distillation it yields guaiol or 
tiglic aldehyde (Part II. p. 410), guaiacol, creosol (Part IV. p. 32), 
and pyroguaiacin, C,,H,.O3, while on heating with zine dust, 
toluene, creosol, metaxylene, paraxylene, pseudocumene and 
guaiene, C,,H,,, are formed.” 

Guaiacum resin contains a dibasic acid, euaiacic acid orguaiaca- 
resin acid,’ which crystallizes from dilute alcohol in small lustrous 
plates and from acetic acid in brittle needles, containing one 
molecule of water. It melts with loss of this at 75°—80° and 
gives a deep grass-green colouration with ferric chloride in 
alcoholic solution. On fusion with caustic potash, proto- 
catechuic acid is formed, while on dry distillation it yields 
guaiacol and a smaller quantity of pyroguaiacin. 

Pyroguaiacin, O,,H,.03, crystallizes from boiling absolute 
alcohol in lustrous, rhombic plates, which melt at 180°5°; it boils 


1 «Of the wood called Guaiacum that healeth the Frenche Pockes and also 
helpeth the goute in the feete, the stoone, the palsey, lepree, dropsy, fallynge euyll, 
and other dyseases.” 

2 Botsch, Monatsh. Chem. i. 615. 

3 Hlasiwetz, Ann. Chem. Pharm. exii. 182 ; Hlasiwetz and v. Gilm, 77d. exix. 
266 ; Hlasiwetz and Barth, tbid. cxxx. 346; Hadelich, Jahresber. Chem. 1862, 
466. 


i 


POLYTERPENES, 485 


at 258° under a pressure of 80—90 mm. and forms a_ blue 
solution in sulphuric acid, decomposition taking place. Its vapour 
density has been found to be 9°53. When it is dissolved in 
absolute ether and treated with potassium, the compound 
C,,H,,K,O, separates out as a white powder. 

Diacetylpyroguaiacin, C,,H,,0(0CO.CH,),, is obtained by 
treating pyroguaiacin with acetyl chloride and crystallizes from 
alcohol in lustrous needles, which melt at 122°. 

Guaiene, C,,H,,, 1s formed when proguaiacin is heated with 
zine dust.!. It crystallizes in large, lustrous plates, which show 
a faint fluorescence, have a faint but characteristic smell, melt 
at 100°—101° and are readily volatile, forming a vapour which 
has the sp. gr. 5°4. It is oxidized by chromium trioxide in acetic 
acid solution to guavenequinone, C,,H,)O0., which readily sublimes 
in lemon-yellow needles, melting at 121°—122°; its vapour 
possesses a tolerably strong odour. 


POLYTERPENES (C,,H,,)n. 


2547 Caoutchouc had long been known to the natives of 
South America and India before it was heard of in Europe. It 
appears to have been first mentioned by Herrera (1549—1625), : 
the celebrated Spanish historian, who relates in his account of 
the second voyage made by Columbus, that in Hayti a game 
was played with balls made of a gum, the description of which 
agrees with that of caoutchouc. Torquemade then relates in 
his Monarquia Indiana, 1615, that a gum is extracted in Mexico 
from the sap of the Uléquahil tree (Custilloa elastica), which is 
employed for preparing shoes and various water-tight articles, 

Caoutchouc however first became known in Europe through 
Condamine, who in 1786 described his journeys in South 
America to the French Academy, and stated that the 
Indians prepare a kind of gum from the sap of the 
caoutchou tree, which is employed for making boots and 
water-tight articles and other purposes. This substance was 
called Hhévé in the province Esmeraldes, and wrapped in 
banana leaves and used for torches, which were two feet long 
and burnt for twenty-four hours. In France it received the 


1 Wieser, Monatsh. i. 594. 


486 AROMATIC COMPOUNDS. 


name gomme elastique, from which the term gummi elasticum 
has been derived. 

The trees which yield South American caoutchouc are 
varieties of the species Hevea or Siphonia, as it is now usually 
termed. ‘To the latter expression corresponds the Portuguese 
Seringa, since the caoutchouc was employed for making syringes. 
(Seringa, lat. Sipho). 

The occurrence of caoutchouc in India was first observed by 
Roxburgh, the celebrated botanist, who, when staying at 
Calcutta in 1810, received a present from Assam of a wide- 
mouthed, four-sided bottle made of bamboo, which was filled with 
honey, and with it the information that the interior of the 
bamboo case was coated with the gum of a tree. This interested 
him more than the honey, and to his surprise he found that the 
coating consisted of caoutchouc. He succeeded in finding the 
tree from which it was obtained and described it in his Flora 
Indica as Ficus elastica, mentioning that caoutchouc was also 
employed for making candles and torches. After the annexation 
of Assam by the English, the East India Company offered a 
prize for further information concerning the tree, a company 
was formed for its cultivation and scientific men named by the 
Government to examine the question. Griffith tells us that the 
Indiarubber tree, known to us only as an ornamental shrub, 
exceeds all the trees of the tropical forest in height and expanse, 
and can be recognized at a distance of several English miles by 
its dense foliage. One of these gigantic trees had a circum- 
ference of twenty-four yards, or forty-three yards if the 
supporting branches be included, these forming independent 
roots and growing along with the parent tree. Its height was 
more than thirty-two yards, and it shaded a circle of 195 yards 
in circumference.! 

In addition to these trees, caoutchouc is also obtained from 
other plants, which will be subsequently mentioned. Itis widely 
disseminated throughout the vegetable kingdom, and, according 
to Schleiden, is found in all milky saps, such as those of the various 
species of Ficus and Papaver, so that it is also contained in opium, 
Cichorium, Lactuca, Sonchus, Asclepias, Euphorbia, &c. It is 
disseminated throughout the sap in small globules, like butter in 
milk, and separates like cream on standing. Many varieties of 
it are met with in commerce. 


1 Ann. Chem, Pharm. xxxi. 347. 


CAOUTCHOUC. 487 


Para caoutchoue or Seringa fina is the best kind and is ob- 
tained in the district of the Lower Amazon from Siphonia 
brasiliensis, while it is extracted on the upper reaches of this 
river and on the Rio Negro from the sap of S. lutea et brevifolia 
and in Cayenne from that of S. elastica. 

Condamine relates that the natives make clay moulds in the 
form of bottles, shoes, &c., dip them in the sap and then dry 
them at the fire, this being repeated until a layer of the required 
thickness has been obtained. The mould is then broken or 
softened by water and removed. 

An eye-witness gives the following account of the process 
carried out in the Para district: 

“The Indians unite together generally in a pretty good 
number, and proceed to discover some spot in the virgin forest 
where there are rubber trees. As soon as they have found such 
a place, they cut paths through the wood to it. This is the sole 
difficulty experienced in procuring rubber, but it is a great one, 
as, owing to the fertility of the soil, the vegetation forms an 
almost closed mass, and every step must be gained by the axe. 
As soon as this labour is accomplished, they make an incision in 
the tree, at the height of a man’s body from the ground, and 
arrange rude bowls of clay which hold about a tumbler full, 
stick the bowls to the trees a little below the incision, and collect 
therein the milk running out; such a bowl is filled in about 
three hours if the tree be fruitful. When the first cutting ceases 
to yield, they make a second one some distance lower down, 
and so on until they have exhausted the milk in the tree 
which is done by making in all four incisions, all at equal 
distances.” 4 

Instead of the clay mounds, pear-shaped, spherical, or even 
flat. pieces of wood are employed, and the Indians of the interior 
employ the paddles of their canoes, These are covered with a 
layer of clay and then employed as already described. The 
rubber is then dried by holding the mould in the thick smoke 
emitted by burning heaps of Urucari or Inaja nuts, the kernels of 
a palm (Attalea excelsa et speciosa), this smoke being supposed to 
impart a special quality to the goods. The Para caoutchouc 
comes into the market in the form of pockets or bottles of 12 cm. 
diameter and 5 cm. thickness, or in round pieces of the same 
thickness, and about 20 cm. diameter. Speckled gum, which is 


1 Hancock, Caoutchouc or India-Rubber Manufacture, London 1857, p. 154. 
297 


488 AROMATIC COMPOUNDS. 





white internally, is obtained by pouring the sap on to thick 
earthenware plates and allowing it to dry; it forms tablets about 
60 cms. square and 5—8 cms. thick. The caoutchoue which 
dries on the incisions in the trees and in the various vessels is 
made up into balls, which are called negro heads. 

A quality which stands near in value to that from the Para 
district is Ceara scrap from Manihot Glazionu, a tree which 
grows on the landward side of Ceara in Brazil. In order to 
obtain the sap, the lower part of the stem is laid bare as far as 
the milk vessels, and the sap allowed to flow on to large leaves 
which are spread upon the ground. Here it dries in long threads 
or sticks, and is either sent into the market in this form or simply 
made up into balls. 

West Indian caoutchouc is extracted in Mexico and Central 
America from the Arbol del Ulé, which has already been men- 
tioned. In San Salvador the milk sap is mixed with water and 
allowed to stand until the caoutchouc has separated as a cream ; 
the turbid water is then drawn off, and this operation repeated 
until it flows away clear. The mass of caoutchouc is then treated 
with a little alum solution, which rapidly causes it to set, after 
which it is pressed and dried in the shade. The same process 
is applied in Carthagena and other districts, such as the neigh- 
bourhood of Pernambuco in Brazil, where the juice of Hancornia 
speciosa is employed. 

This variety of caoutchoue occurs in commerce in lumps or 
large blocks made up of a number of plates pressed together. 
In Panama and Nicaragua the sap of Jpomea bona nox, is 
added to the milk sap, which is thus speedily coagulated, the 
caoutchouc separating out as a mass smelling like fresh cheese, 
which is then simply pressed and made into tablets. 

East Indian caoutchouc is, as already mentioned, obtained from 
Ficus elastica, a tree which is now cultivated inUpper India, Lower 
India, the Malay Archipelago, Angola, and Nubia. Griffith re- 
lates that in Assam the roots are laid bare, incisions made and 
a hole dug out underneath, in which a leaf of Phrynium 
capitatum, folded in the shape of a basin, is laid. At the present 
time incisions are made in the stem and the juice collected in 
wooden vessels; the caoutchouc is then allowed to separate, 
heated with water and finally well-pressed and dried. | It comes 
into the market in lumps, which are made up of dark and light- 
coloured pieces kneaded together. 

Borneo caoutchouc. Mr. James Howison, an English surgeon, 


CAOUTCHOUC. 489 





residing in Penang, is the authority for the following fact, taken 
from a memoir published by him in the year 1798: “ While 
clearing a way through jungle with cutlasses, it was remarkable 
that a vine had been divided, the milk of which, drying on 
the blade of the weapon, possessed all the properties of American 
caoutchouc.”+ He described the plant, to which Roxburgh gave 
the name of Urceola elastica. It is found in Borneo, Sumatra, 
and the other Malay Islands, and forms a stem as thick as a 
man’s arm and more, creeping along the ground to a great 
length and then rising upon the highest trees. Its small 
greenish flowers have the shape of a pitcher (w/ceus), and its 
milk-sap, as well as that of several species of Willughbeia, 
which are also climbing plants, and like Urceola belong to 
the family of Aporcynaceae, is now used for the extraction of 
caoutchouc, for which purpose it is simply coagulated by the 
addition of salt water. Borneo caoutchouc occurs in porous 
lumps or balls saturated with salt water. It contains the methyl 
ether of dambose, which has recently been recognised as 
identical with imosite, and has been found not to belong to the 
sugar group but to be hexhydroxyhexmethylene, C,H,(OH),.” 

African Caoutchouc. The whole of tropical Africa is pene- 
trated by a belt of rubber-producing climbing plants, which are 
used for the extraction of caoutchouc. The various species 
of Landolphia, yield the rubber of the Gold coast, while Lagos 
rubber is obtained from Ficus Vogelii the operation being 
carried out however with so little care that the product is only 
of small value. Madagascar and Mozambique, on the other 
hand, yield a product which stands next to the Para variety in 
value. It is obtained from Vahea madagascariensis et gummt- 
fera, climbing shrubs or trees, which are now cultivated in 
Java, by coagulation of the milk sap with salt water, or by 
simple drying. This, as has been previously mentioned, con- 
tains matezodambose, a substance closely related to inosite. 
It occurs in commerce in the form of balls or lumps, the best 
variety being reddish coloured, while the inferior qualities are 
black. 

2548 The caoutchouc of commerce contains, according to its 
source, various admixtures, such as albuminoids, coloured sub- 
stances, resin, mineral matter, &c. In order to purify it, it is 
repeatedly extracted with hot water, alcohol and ether, the 


1 Hancock, Joc. cit. p. 158. 
2 Maquenne, Compt. Rend, civ. 225 and 1858. 


490 AROMATIC COMPOUNDS. 


residue dissolved in chloroform and the clear solution pre- 
cipitated with alcohol. It is thus obtained as a colourless 
mass, resembling gum arabic! Faraday, who examined a 
specimen of sap which Hancock had received from South 
Mexico in a sealed bottle, found in it 31:7 per cent. of caoutchouc, 
which he obtained pure by distilling the liquid with water, re- 
peatedly shaking the separated cream with water containing 
hydrochloric acid, and then drying it on a porous plate. He 
thus obtained a colourless, opaque, elastic film, which, after the 
removal of all water, became transparent and showed all the 
properties of commercial caoutcbouc.. Nees von Esenbeck and 
Marquart allowed the liquid exuding from Ficus religiosa to run 
into ether and thus obtained a syrup, which on the addition of 
more ether deposited a sediment. The clear liquid decanted 
from this, left on evaporation a colourless, elastic mass, which 
still contained wax, this being however removed by boiling with 
alcohol? 

According to the analyses of Faraday and Payen, caoutchouc 
contains seven atoms of hydrogen to every four atoms of carbon. 
G. Williams however showed that it follows from the com- 
position of its distillation-products that it is polymeric with 
oil of turpentine, and Bouchardat arrived at the same con- 
clusion, which was confirmed by Adriani’s analysis of purified 
caoutchouc. It is however very difficult to obtain a specimen 
of caoutchouc entirely free from oxygen (Gladstone and 
Hibbert).? 

Caoutchouc has a faint but very characteristic smell; at the 
ordinary temperature it is soft, very elastic and tough; freshly 
cut surfaces are adhesive and may be firmly welded together, a 
property which was formerly made use of in the laboratory for 
the preparation of tubes, while below 0° it becomes hard and less 
pliable and elastic. It is tolerably hygroscopic and swells up and 
becomes adhesive in boiling water, this also taking place, as is 
well known, when it is chewed for a considerable length of time, 
but it regains its original properties after drying. It also absorbs 
alcohol and therefore swells up in this liquid more readily when 
the mixture is warmed. When well dried, it dissolves in ether, 
chloroform, benzene, oil of turpentine, oil .of lavender, fused 
naphthalene and other hydrocarbons, as well as in carbon 
disulphide, its solubility in the latter being very much increased 


1 Adriani, Jahresber. Chem. 1850, 621. 2 Ann. Chem. Pharm. xiv, 48. 
3 Journ. Chem. Soc. Trans. 1888, 679. 





CAOUTCHOUC. 491 





by the addition of 8 per cent. of absolute alcohol! It is a non- 
conductor of electricity and becomes strongly electrified when 
rubbed (Faraday). Exposed to the light it absorbs oxygen from 
the air and becomes brittle.? Spiller found in one case that the 
thin caoutchouc layer on the waterproof material employed for 
packing had gradually changed into a resin which resembled 
shellac, was insoluble in alcohol and had the empirical formula, 
C,,H,,03.2 Caoutchouc stoppers, tubes, etc., should therefore be 
preserved in well closed vessels in the dark ; if they become 
hard their pliability may be restored by exposing them first to 
the vapour of carbon bisulphide and then to that of petroleum.* 
If a sheet of paper be covered with a solution of caoutchouc in 
benzene, and the layer thus obtained exposed to the light under 
a photographic negative and then transferred to a lithographic 
stone, printer’s ink will only be taken up by the portions covered 
by the dark parts of the negative. Caoutchouc loses its tough- 
ness and elasticity when it is allowed to remain in contact with 
fats or oils. 

Gladstone and Hibbert have determined the specific refraction 
of caoutchouc, and conclude that the group C,,H,, contains three 
double linkings and is an open chain. They have further found 
that pure caoutchouc does not melt in absence of air even at 
200°, and that its solution in toluene retains its optical properties 
at this temperature. An ordinary specimen, however, commences 
to melt at about 120° and remains soft and adhesive after 
cooling, but becomes hard again when spread out in thin layers, 
If on the other hand it be heated to 200° it passes on cooling 
into a slimy mass, which does not become hard. On dry dis- 
tillation it yields isoprene, C;H,, dipentene, C,,H,, (p. 455), and 
heveene, C,,H,, (p. 480). 

Isoprene is a liquid, which boils at 37°,° and is probably identical 
with valerylene. It is converted on heating, as already men- 
tioned, into dipentene. If it be repeatedly agitated with 
concentrated hydrochloric acid throughout a considerable period, 
diluted with water and distilled, the compounds, C;H,Cl and 
C,H,,Cl,, pass over and a solid substance remains, which after 
extraction with boiling water still contains 17 per cent. of 
chlorine, but in other respects possesses the properties and com- 

1 Payen, Jahresber. Chem. 1852, 638. 

2 Adriani, doc. cit. ; Miller, Journ. Chem. Soc. [2] iii, 1738. 
3 Thid, [2} iii. 44, 

* Hempel, Ber. Deutsch. Chem. Ges. xv. 914. 

5 Williams, Journ. Chem. Soc. [1] xv. 110. 


492 AROMATIC COMPOUNDS. 





position of caoutchouc.! If chlorine be passed into a solution of 
caoutchouc in chloroform, the compound, C,,H,,Cl,, is formed 
which remains on evaporation in yellow scales. Bromine first 
produces the compound, C,,H,,Br,, which on further action 
is converted with evolution of hydrobromic acid into a 
compound C,,H,,Br;, which is precipitated by ether in white 
flakes (Gladstone and Hibbert). 

2549 Caoutchouc finds numerous applications and is of the 
utmost value to the chemist. Liebig says in his Letters on 
Chemistry : 

“Tf it be attempted to describe the progress and development 
of modern chemistry, a eulogy of the materials and tools which 
are helpful to the chemist in his work cannot be omitted. Without 
glass, cork, platinum and caoutchouc, we should probably not have 
made nearly such great advances. . . . 

“By means of cork we unite wide with narrow openings and 
by means of cork and caoutchouc together we are enabled to 
construct the most complicated glass apparatus without the 
aid of the mechanic, or of screws and taps... . 

“Without cork and caoutchouc we should be dependent on 
the mechanic in all our work. Without caoutchouc alone, 
apparatus would be more costly and more fragile; the chief 
advantage granted by both lies however in the saving of 
invaluable time.” 

After Condamine had made the scientific world acquainted 
with caoutchouc, the French Academy received further in- 
formation concerning it from Fresneau in 1751, and from 
Macquer in 1768. The latter mentioned in his account the 
fact that small tubes might be made by spreading a solution 
of caoutchone in ether over suitable moulds. It was however 
at first used entirely for rubbing out pencil marks and thence 
received the name of India-rubber in this country. Priestley, 
in the preface to “A Familar Introduction to the Theory 
and Practise of Perspective,’ 1770, says, “I have since the 
printing of this work seen a substance which is excellently 
adapted for expunging pencil marks. It is sold by Mr. Nairne, 
opposite the Royal Exchange, who asked three shillings for half 
a square inch of it, but assured me that it would last for several 
years.” 

Hancock states that one ounce of bottle caoutchouc cost a 


1G. Bouchardat, Compt, Rend. Ixxxix. 1117. 


CAOUTCHOUC. 493 





guinea, but in spite of this high price he divined that it might 
be employed for more important purposes than rubbing out 
pencil marks, and in 1820 he cut out rings and bands of it 
which were used for fastening gloves, and as garters, braces, etc. 
In this way he obtained much waste which he could not make 
use of, this being also the case with the irregular masses 
occurring in commerce. After long-continued experiments he 
succeeded in finding a method by means of which caoutchouc of 
every description can be converted into completely homogeneous 
and regular masses, from which blocks, tablets, &c., may be 
prepared, and the wished-for articles cut out of these. The 
machine employed for this purpose he called a masticator. 

About this period, Macintosh, chiefly with the view to the 
production of ammonia to be employed in the manufacture of 
cudbear (Pt. IV. p. 44), entered into a contract to receive for a 
term of years the tar and ammoniacal water produced at the 
Glasgow Gas Works. After the separation of the ammonia in 
the conversion of the tar into pitch, to suit the purposes of con- 
sumers, the oil termed naphtha is produced ; and the thought 
occurred to him of its being possible to render this also useful, 
from its powers as a solvent of caoutchouc, or India-rubber. 
By exposure to the action of the volatile oil termed naphtha, 
obtained from the coal tar, he converted this substance into a 
waterproof varnish, the thickness and consistency of which he 
could vary according to the quantity of naphtha which he 
employed in the process. He subsequently developed the 
further technical applications of caoutchouc in conjunction with 
Hancock, and the latter finally became a partner in the well- 
known firm of Charles Macintosh and Co., which transferred its 
works to Manchester. 

The caoutchouc of commerce contains various mechanical 
admixtures. It is purified by first softening it in hot water, and - 
then cut up into small pieces by a rapidly rotating circular knife, 
kept cold by a stream of water. These are then passed between 
rollers, also cooled by water, and the broad ragged masses thus 
obtained dried. In order to convert these into a homogeneous 
mass, the masticator, also called the kneader or wolf, is employed. 
It consists of a strong, fluted iron cylinder, in which a thick 
wooden cylinder, studded with teeth, revolves, which kneads the 
rubber very effectually, and thereby heats it so much that a stream 


1 Hancock loc. cit. Preface v. 


494 AROMATIC COMPOUNDS. 


of cold water has to be kept running on to it, the temperature of 
the mass rising to 70° when this was not used (Hancock). This 
machine has now been replaced by two rollers, which can be 
brought within 60-30 mm. of each other, and are heated by 
steam, a coherent leaf of rubber being obtained, which is crushed 
up and again rolled until the mass has become perfectly homo- 
geneous, after which it is pressed in blocks. In order to colour the 
rubber black, lampblack from pine-wood is added, while a red 
colour is obtained by the addition of precipitated antimony 
sulphide, and a white by zine white. 

The blocks thus obtained are then cut or rolled cate plates 
which are then worked up into tubes, cylinders, threads for 
elastic material, &c. Very thin sheets are prepared by moisten- 
ing caoutchouc with solvent naphtha or carbon bisulphide, and 
spreading the resulting paste on a flat surface. 

The natives of Mexico and Brazil were acquainted with the 
method of making articles water proof by means of the milk sap 
of the caoutchouc tree. A process for this purpose was patented 
in 1791 by Peal, who proposed to employ oil of turpentine as the 
solvent, but this method only became of practical importance in 
the hands of Macintosh. In order to prepare such materials, 
caoutchouc is mixed with sufficient naphtha or oil of turpentine 
to produce a thick varnish, with which the article in question is 
smeared, It is then laid on another piece covered with a thiner 
layer, and finally passed between rollers. Thicker materials are 
also made by placing a thin sheet of caoutchouc between two 
pieces of the stuff, while a thinner article is procured by simply 
laying a thin sheet on the material and passing the whole 
between heated rollers. 

Liidersdorf of Berlin found in 1832 that when caoutchouc is 
mixed with sulphur, it loses its adhesiveness, and in 1839 Good- 
year took out a patent in America for sulphuretted caoutchouc, 
the manufacture not being further described. In 1842 however 
he brought into the market rubber shoes which retained their elas- 
ticity even in the cold. The action of sulphur on caoutchouc was 
investigated at about this time by Brockedon and Hancock, the 
latter of whom found that caoutchouc absorbs fused sulphur 
without being altered to any great extent. 

If, however, the temperature be raised above the melting 
point, caoutchouc acquires new and very important properties. 
Following a suggestion of his friend Brockedon, Hancock termed 
this new process vulcanization. The name “ owes its derivation 


CAOUTCHOUC. 495 





to the Vulcan of mythology, as in some degree representing the 
employment of sulphur and heat, with which that Pee 
personage was supposed to be familiar.” 

According to Payen, vulcanization takes place at 132°—140° 
in a few minutes. India-rubber cuttings are usually mixed with 
7-10 per cent. of sulphur, and the whole repeatedly rolled out 
and then heated to 140°—150°. 

Parkes has introduced a process by which purified india-rubber - 
or articles made from it are vulcanized in a cold mixture of 
100 parts of carbon disulphide and 2°5 parts of chloride of 
sulphur, and are then simply washed with lukewarm water and 
dried. Thick articles must be repeatedly dipped into the 
solution, while it is applied to waterproof fabrics by means of a 
sponge. An excellent method, which has been proposed by 
Gérard, consists in soaking the caoutchouc for some hours in a 
solution of potassium pentasulphide of sp. gr. 1°25 heated to 
140°, after which it is washed and dried. 

Vulcanized india-rubber has a grey colour, and is not 
adhesive. It remains very elastic and pliable even in the cold, 
and only swells up, without dissolving, in the solvents of 
ordinary caoutchouc. It contains 1—2 per cent. of sulphur 
chemically combined; the remainder is simply mechanically 
mixed with the indiarubber and can be extracted by boiling 
with caustic soda, a process which prevents vulcanized india- 
rubber from becoming hard and brittle. According to Hancock, 
it also becomes brittle when too much sulphur or too great a 
heat has been employed in its manufacture. A new industry, 
that of vulcanite or ebonite, was founded upon this property by 
Goodyear in 18538. When caoutchouc is heated to 150° with half 
its weight of sulphur, a plastic mass is obtained, which on cooling 
becomes as hard and tough as horn and can be worked in the same 
way as the latter. Ebonite forms an excellent isolator for electrical 
apparatus and becomes strongly electrified when rubbed. 

The applications of vulcanized indiarubber are exceedingly 
numerous, It is employed, for example, in making elastic ma- 
terials, surgical instruments, travelling bags, door-mats, shoes, 
macintoshes, life-boats, diving dresses, tires for wheels, tubes 
of all kinds, &c. 

Vulcanite is chiefly used for making combs, penholders, knife 
handles, surgical and musical- instruments, silver-baths for 
photography, cells for galvanic batteries, plates for electrical 
machines, casts of art objects, &c. 


496 AROMATIC COMPOUNDS. 


In the year 1886, 9265 tons (about 10 million kilos.) of 
caoutchouc, worth £2,202,746, were imported into England. 
Of this 5470 tons, valued at £1,281,499, were exported chiefly 
to Germany, Russia, and United the States of America.} 

2550 Guttapercha occurs in the milksap of Jsonandra Gutta, a 
lofty tree, which grows on the Malay peninsula, as well as on 
Sumatra, Borneo and other islands of the Malay archipelago, and 
is called percha by the natives, gutta being Malay name for gum. 
Sticks, riding whips, and other small articles of a similar nature, 
made of this substance, were brought to Europe in the seven- 
teenth century as curiosities, but they excited no special curiosity. 
Dr. Montgomery, living at Singapore, was the first in 1842 to draw 
attention to the valuable properties of this substance, and 
specimens were brought to England during the following year by 
Joze d’Almeida and exhibited at meetings of the Royal Asiatic 
Society. Its value was quickly recognised; two hundred weights 
of it were shipped to England in 1844, while the amount 
imported during 1880 amounted to 65,856 ewt. (3,345,484 kilos.), 
worth £527,872." 

In order to obtain guttapercha, the trees were formerly 
simply felled, incisions made in the bark and the sap collected. 
At present the trees are tapped and the guttapercha, which 
separates from the sap on standing or heating, kneaded 
thoroughly with the hands, after which it is made into blocks 
and dried. Guttapercha also occurs in the saps of some other 
trees, which, like Jsonandra belong to the Sapotacew. Especially 
rich in it is Bassia Parkii, a tree very widely distributed over 
equatorial Africa, and whose fruits, allied to shea-butter (Part I. 
p. 678) yield galam-butter. This discovery of a new source of 
guttapercha is of the highest importance, because the Malays 
treat their trees in so barbarous a manner that they will soon 
become extinct. The guttapercha of trade is a reddish, marbled 
mass, with which sand, bits of wood, portions of bark, &c. are 
incorporated. It is purified on the large scale by being cut up 
into fine shavings, thoroughly mashed and then formed into 
blocks by kneading. It may be obtained perfectly pure and 
colourless by boiling out with alcohol, dissolving the residue in 
chloroform or hot benzene, if necessary decolorizing the solution 
with animal charcoal, and then precipitating with alcohol. Its 

1 Watson Smith, Journ. Soc. Chem. Ind. vi. 766. 


2 Spon’s Lncyclop. 1653. 
3 Heckel and Schlagdenhauffen, Compt. Rend. c. 1238 ; ci. 1069. 


- ss ———— 


GUTTAPERCHA. 497 





composition has been determined by Hofmann,! Baumhauer,? 
Adriani.? It dissolves in all the solvents of indiarubber.t . At 
the ordinary temperature it is hard, tough, and only slightly 
elastic, but becomes pliable at 25°, and gradually softens on 
heating, being so plastic at 60° that it may be pressed into any 
shape or drawn out into threads or bands, and becoming adhesive 
at 100.° It swells up to some extent in boiling water and may 
then be drawn out into threads, having thus taken up 5—6 
per cent. of water, which is only gradually lost on exposure to the 
air, At about 150° it becomes liquid and decomposes at a 
higher temperature, yielding the same products as caoutchouc 
(Williams). Like the latter, it absorbs oxygen in the sunlight, 
becoming brittle, and is also quickly acted upon by ozone. 
It may be preserved in the dark or under water, especially sea- 
water, without undergoing any alteration. 

The guttapercha industry, like that of indiarubber, was 
founded by Hancock and Goodyear, who noticed that it too 
is rendered unchangeable in air or sun-light by the process 
of vulcanization, which also deprives it of the property of 
softening when heated. Guttapercha is employed for almost 
innumerable purposes, since it becomes plastic when heated and 
retains the form imparted to it on cooling; it is not attacked by 
alkalis and acids, including even hydrofluoric acid,°® nor is it 
surpassed by any other substance as a non-conductor of 
electricity. It possesses moreover, as a conductor of sound 
waves, remarkable accoustical properties. 

The addition of more sulphur imparts to guttapercha the 
properties of ebonite, and hence it is employed for similar pur- 
poses. According to Macintosh, it is also hardened by the action 
of concentrated sulphuric acid, after which treatment it must be 
very thoroughly washed with water. It is frequently mixed in 
various proportions with caoutchouc in order to increase its 
elasticity. 

Bleached guttapercha serves as a filling for teeth, and is 
used in the preparation of sets of artificial teeth. It is also 
employed for surgical purposes as guttapercha paper (Gutta 
lamellata), while a solution of guttapercha in chloroform, which 
is known as traumaticin, finds application as a substitute for 
collodion. | 

1 Ann, Chem. Pharm. cxv. 297. 2 Journ. Prakt. Chem. \xxviii. 277. 


3 Jahresber. Chem. 1860, 96. 4 Payen, tid. 1852, 637. 
5 Stideler, Ann. Chem. Pharm. lxxxvii. 137. 


498 AROMATIC COMPOUNDS. 


2551 Lalata is obtained from the sap of Mimusops Balata, a 
tree indigenous in Guiana and Brazil. The commercial product 
forms a leathery mass and contains oxygen. The pure com- 
pound isolated from this is isomeric with caoutchouc and gutta- 
percha,! and is moreover elastic like the former and becomes 
plastic like the latter on heating. It dissolves in the same 
solvents as its isomerides and can also be vulcanized. 

It was formerly employed for coating telegraph wires, for 
isolators, surgical instruments, &c., but is now used in the 
United States as “chewing gum,” fifty tons per annum being 
consumed for this purpose. Its production has recently decreased, 
because the tree, which grows in extremely unhealthy districts, 
is no longer cultivated and is gradually dying out.” 

Helenite was found among the earth thrown up from one of 
the shafts at the Ropa petroleum works. It occurs in thin 
lamine, 10—15 cm. long, and 4—5 cm. wide, which, after 
treatment with ether to remove liquid hydrocarbons, are white 
and faintly translucent, becoming elastic when immersed in 
water. On heating it gives off vapours having the smell of 
those of Para-rubber. It is soluble in the same solvents as india- 
rubber, and can also be vulcanized, so that it appears to be a 
fossil india-rubber.® 

Coorongite is the name given to a rubber-like mass, which was 
discovered in 1866 in Coorong, in South Australia, where it 
occurs in tolerably thick layers, lying on the sand. Nothing is 
definitely known as to its origin, but it is probably a fossil resin. 

When submitted to dry distillation it yields about 82 per cent. 
of liquid and gaseous hydrocarbons.‘ 

Dammar Resin is derived from the Amboyna pine, Dammara 
orientalis, which grows in the same countries as the guttapercha 
tree. The natives employ it as incense and for candles, which 
are made by enveloping the powder with palm leaves or filling 
itinto pines of bamboo. In this country it is used for varnishes 
and lacquers. It contains a number of oxygenated compounds, 
accompanied by dammaryl (C,)H,,), which may be isolated by 
extracting the resin with hot alcohol, treating the residue with 
ether, concentrating this solution and pouring it into water. It 


1 Sperlich, Jahresber. Chem. 1869, 789. 
2 Spon’s Encyclop. 1635. 
3 Nawratil, Ber. Deutsch. Chem. Ges. xvi. 2312. 


4 Jahresber. Chem. 1872, 1147; Heinzerling, Kautschuk- und Guttapercha- 
waaren, 


DAMMAR RESIN. 499 


is thus obtained as a lustrous amorphous powder, which melts 
at 190° and absorbs oxygen from the air.! 

Fichtelite occurs in a peat bed near Redmitz in the Fichtcl- 
gebirge, and is also found in fossil pines in the form of scales 
or flat needles; it has also been met with in a peat-bog at 
Franzenbad and in Denmark. It crystallizes from alcohol in 
monoclinic tablets, which melt at 46° and distil above 320° 
without decomposition.” 

Hartite, which occurs in deposits of brown coal, is very similar 
to fichtelite, but melts at 74°.3 

A number of other fossil polyterpenes are also known. 


1 Dulk, Journ. Prakt. Chem. xlv. 36. 

2 Bromeis, Ann. Chem. Pharm. xxxvii. 304; Steenstrup and Forchhammer, 
ibid. xli. 42 ; Clarke, zbid. cili, 326. 

3 Haidinger, Pogg. Ann. liv. 261; Schrotter, ibzd. lix. 48. 





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INDEX. 


A. 


ABSINTHOL, 475 
Acetamidopentamethylbenzene, 344 
Acetmesidide, 117 
Acetobenzalacetic acid, 360 
a-Acetocinnamic acid, 360 
Acetocinnamone, 336 
Acetophenone-acetone, 358 
Acetophenone-acetonecarboxylic acid, 
385 
Acetophenone-acetoxime, 57, 358 
Acetophenone alcohol, 61 
Acetophenonecarboxylic acid, 149 
Acetophenonephenylhydrazine, 57 
Acetophenonesulphonie acid, 59 
Acetorthamido-acetophenone, 58, 59 
Acetorthoamidophenylacetic acid, 22 
Acetoxindol, 22 
a-Acetpseudocumide, 119 
Acetylaniline, 58 
Acetylbenzol alcohol, 61 
Acetylbromisatic acid, 86 
Acetylbromopseudo-isatin, 86 
Acetyleoumaric acid, 240 
Acetyldioxindol, 54 
Acetyleugenol, 199 
Acetylferulic acid, 251 
Acetylhydridinie acid, 54 
Acetylhydromethylketol, 268 
Acetylindol, 39 
Acetvliodobenzene, 57 
Acetylisatic acid, 86 
Acetylisoferulic acid, 251 
Acetylmethylketol, 372 
Acetylorthamidomandelic acid, 54 
Acetylparacoumaric, 248 
Acetylparamethylisatic acid, 91 
Acetylparamethylpseudo-isatin, 91 
Acetylphenol, 59 
Acetylpseudo-isatin, 85 
Acetyltolylparamethylimesatin, 89 
Acetylumbelliferon, 254 
Acid barium trimesate, 139 


298 


Acid calcium hydroxytrimesate, 142 

Acid methyl camphorate, 444 

Acid sodium cinnamate, 215 

Acid sodium trimesate, 139 

Acide formobenzoilique, 43 

Acids, CgH;C,H,.CO,H, 369 

Acids of the composition, C,H;C,H, 
CO.H, 366 

Acids of the formula C,.H,,0,, 383 

Acids of the formula C,,H,,0., 389 

Acids of the formula C,H 3)0., 480 

Addition products of camphor, 439 

#Esculetin, 256 

ZEseulin, 258 

African caoutchouc, 489 

Aimethylhomophthalimide, 151 

Alantol, 474 

Alcohols of the formula C,,H,,_.0, 398 

Alcohols of the formula C,H,,_,0, 402 

Aldehyde camphor, 439 


Aldehydo-a-hydroxyisophthalic acid, 
141 
Aldehydo-v-hydroxyisophthalic acid, 


141 
Allyleugenol, 199 
Allylenephenyl, 196 
Allylisopropylbenzene, 389 
Allylphenol, 196 
Allylresorcinol methyl ether, 199 
Allyltoluene, 314 
Alphahomoprotocatechuic acid, 25 
Alphahomovanillic acid, 25 
Alphahomoveratric acid, 26 
Alphatoluic acid, 11 
Alphatoluylformic acid, 188 
Aluminium mellitate, 379 
Amenylbenzene, 354 
Amidocamphor, 437 
Amidocarbostyril, 230 
y-Amidocarbostyril, 225 
Amidocetylbenzene, 397 
Amidocinnamic acids, 220 
Amidocoumarin, 246 
Amidocumene, 157 


504 


INDEX. 





a-Amidohydratropic acid, 176 
Amidohydrocarbostyril, 169 
Amidomellitiminic acid, 380 
Amidomesitol, 114 
Amidomesitylene, 117 
a-Amidomesitylenic acid, 128 
B-Amidomesitylenic acid, 128 
Amidometa-isocymene, 303 
Amidomethylethylbenzene, 145 
Amidomethylketol, 267 
Amido-8-methylumbelliferon, 333 
Amido-oxindol, 74 
Amidopentamethylbenzene, 344 
Amidophellandrene, 469 
Amidophenylacetic acids, 19 
Amidopinene, 415 
Amidopipitzahoic acid, 398 
Amidopropiophenone, 161 
Amido-a-pseudocumenol, 115 
Amidoresacetophenone, 60 
a-Amido-uvitic acid, 135 
B-Amido-uvitic acid, 135 
Amidothymol, 300 
Amidotrimethylbenzenes, 117 
Amidotyrosine, 183 
Amidoxindol, 92 
Ammonium dextropimarate, 481 
Ammonium nitrosodioxindol, 54 
Amygdalie acid, 51 
Amygdalin, 49, 51 
Amylamidobenzene, 352 
Amylbenzene, 351 
Amylbenzoic acid, 383 
Amyleugenol, 199 
Amylene, 464 
Amylphenol, 352 
Amyltoluenes, CH .C,H4.C3H;(CHs)o, 
382 
Amylxylene, 394 
Andropogon, 471 
Anethol, 196, 200, 201 
Anhydride, 151 
Anhydride of abietic acid, 482 
Anilidopipitzahoic acid, 398 
Anisoin, 197 
Anol, 196 
Anthemol, 454 
Anthemy] alcohol, 454 
Anthroxanaldehyde, 99 
Anthroxanic acid, 99 
Argentammonium mellitimide, 380 
Aromatic substitution products of man- 
delice acid, 51 

Asa foetida, 250 
Asaron, 202 
Atroglyceric acid, 194 
Atroglyceronitril, 194 
_ Atrolastie acid, 175 

Atropic acid, 233 
Atropine, 177 
Atroxindol, 163 
Austracamphene, 409, 417 
Australene, 409, 415 
Azocymene, 293 


Azodioxindol, 55 
Azopseudocumene, 110 
Azoxindol, 55 


B. 


BALATA, 498 
Bang Phien, 420 
Barium camphanate, 447 
Barium chlorotrimesate, 142 
Barium cinnamate, 215 
Barium-cumene-orthosulphonate, 156 
Barium cumeneparasulphonate, 155 
Barium dioxindol, 53 
Barium ethylisatate, 85 
Barium hemimellithate, 141 
Barium hydrocinnamate, 165 
Barium hydroxytrimesate, 142 
Barium isatate, 77 
Barium isatinsulphonate, 83 
Barium isoxylate, 125 
Barium laurenesulphonate, 347 
Barium mellitate, 379 
Barium mesitylenate, 124 
Barium nitroso-dioxindol, 54 
Barium orthonitrophenylacetate, 18 
Barium paranitrophenylacetate, 17 
Barium paraxylate, 125 
Barium phenylhydroxyacetate, 45 
Barium phenylpropiolate, 260 
Barium propylbenzeneorthosulphonate, 
158 
Barium propylbenzeneparasulphonate, 
158 
Barium trimellithate, 140 
Barium xylate, 125 
Benzaceto-acetic-ether - orthocarboxylic 
acid, 391 
Benzacin, 15 
Benzalacetone, 336 
Benzal-laevulinic acid, 392 
Benzalmalonic acid, 338 
Benzenepentacarboxylic acid, 345 
Benzenetetracarboxylic acids, 280 
Benzenetricarboxylic acids, 138 
Benzhydrylacetocarboxylic acid, 312 
Benzidene diacetate, 212 
Benzidenephenylhydroxyacetamide, 48 
Benzocyanidrin, 70 
Benzoylacetaldehyde, 185 
Benzoylacetic acid, 185 
Benzoylaceto-acetic acid, 360 
Benzoylacetocarboxylic acid, 316 
Benzoylacetonamine, 323 
Benzoylacetone, 322 
Benzoylacetonitril, 187 
Benzoylacetoxime, 323 
Benzoylacrylic acid, 337 
Benzoylamidocinnamice acid, 188 
Benzoylbutyl alcohol, 392 
Benzoylcarbinol, 61 
Benzoylceyanacetic acid, 326 
Benzoylethidene-aniline, 185 
Benzoyleugenol, 199 
Benzoylformamide, 69 


INDEX. 


Benzoylformic acid, 67 

Benzoylformonitril, 70 

Benzoyl-formyl compounds, 67 

Benzoylhydride benzoate, 48 

Benzoyliso-eugenol, 199 

Benzoyliso-succinic acid, 365 

Benzoylmethy] acetate, 62 

Benzoylmethy] alcohol, 61 

Benzoylmethyl benzoate, 62 

Benzoylmethyl bromide, 61 

Benzoylmethyl chloride, 61 

Benzoylmethyl compounds, 56 

Benzoylmethyl phenyl ether, 62 

Benzoylmethylene bromide, 63 

Benzoylmethylene chloride, 63 

Benzoylmethylene compounds, 63 

Benzoylortho-amido-acetophenone, 58 

Benzoylpropionaldehyde, 322 

Benzoylpropionic acid, 322 

Benzoylpropionorthocarboxylic 
362 

Benzoylpyroracemic acid, 322, 323 

Benzoylsuccinic acid, 364 

Benzoyltrimethylene, 360 

Benzoyltrimethylenecarboxylic 
359 

Benzoyltriméthylene-oxime, 860 

Benzylacetone-orthocarboxylic acid, 359 

Benzylacto-acetic acid, 358 

Benzyl benzylbutyrate, 352 

Benzyl benzylisobutyrate, 352 

Benzylbutyric acid, 352 

Benzyl carbinol, 6 

Benzyl cinnamate, 216 

Benzylglyoxylic acid, 188 

Benzyl hydrocinnamate, 166 

Benzylhydroxybutyric acid, 355 

Benzylhydroxypentylic acid, 393 

Benzylindol, 39 

Benzylindolearboxylic acid, 271 

Benzylmalonic acid, 325 

Benzylmalonic - ether - orthocarboxylic 
acid, 366 

Benzylmalonorthocarboxylic acid, 365 

Benzylmethylglycolic acid, 321 

Benzyl phenylacetate, 13 

Benzylpseudo-isatin, 85 

Benzyltartronic acid, 325 

Bergamene, 411 

Bergamot, oil of, 451 

Bicolorin, 258 

Blastophenylpropionic acid, 162 

Borneéne, 421 

Borneo-camphene, 418 

Borneo-camphor, 419 

Borneo caoutchoue, 488 

Borneol, 419, 428 

Borneol bromide, 421 

Borneol, isomerides of, 471 

a-Bornylacetamide, 424 

Borny] acetate, 423 

Borny] alcohol, 419 

Bornylamine, 432 

a-Bornylamine, 423 


acid, 


acid, 


505 


B-Bornylamine, 424 
a-Bornylamine hydrochloride, 424 
8-Bornylamine hydrochloride, 424 
B-Bornylbenzamide, 424 
Bornyl bromide, 422 

Bornyl carbamate, 423 
a-Bornylcarbamide, 424 
Bornyl carbonate, 422 

Bornyl! chloride, 422 
Bornylene, 417 
a-Bornylformamide, 424 
Bornyl formate, 423 

Bornyl oxide, 422 
Bornylsulphuric acid, 422 
Bornyl valerate, 423 
Bromacetophenone, 62 
Bromethylbenzene, 5 
Bromindazol, 65 

Bromisatin, 80 

Bromisatin chloride, 83 
Bromisatoic acid, 98 
Bromisatoxime, 93 
Bromisodurene, 275 
Bromocamphor, 434 
Bromocamphorcarboxylic acid, 441 
Bromovamphoryl oxide, 445 
y-Bromocarbostyril, 228 
Bromocinnamaldehyde, 209 
Bromocinnamic acids, 218 
a-Bromocinnamic acid, 236 
B-Bromocinnamic acid, 236 
Bromocinnamy] chloride, 236 
Bromocoumaron, 247 
a-Bromocoumarin, 246 
8-Bromocoumarin, 246 
Bromoctylbenzene, 395 
Bromodioxindol, 55 
Bromodurene, 274 
a-Bromohydratropic acid, 176 
Bromohydrocinnamie acids, 166 
Bromo-f-hydropiperic acid, 368 
Bromohydroxypiperinide, 371 
Bromomesityl alcohol, 122 
a-Bromomesitylenic acid, 126 
8-Bromomesitylenic acid, 127 
a-Bromometa-isocymene, 302 
B-Bromometa-isocymene, 302 
Bromopentamethylbenzene, 344 
Bromorthomethylbenzene, 145 
Bromostyrolene dibromide, 33 
Bromotetra-ethylbenzene, 395 
B-Bromothymoquinone, 299 
Butenyl benzenes, 326 
Butenylmethylbenzene, 353 
Butyric-acid-coumarin, 368 
Butyrocoumaric acid, 368 
Butylbenzene, 272, 318 
Butylbenzenes, the, 318 
Butyltoluenes, 348 


C. 


CAFFEETANNIC acid, 249 
Caffeic acid, 249 


506 


INDEX. 





Cajeputene, 455 
Cajuputol, 459 
Calcium atropate, 234 
Calcium camphorate, 444 
Calcium cinnamate, 215 
Calcium ethylcoumarate, 244 
Calcium ethylcoumarinate, 244 
Calcium hemellithate, 126 
Calcium hydratropate, 163 
Calcium hydrocinnamate, 165 
Calcium isoxylate, 125 
Calcium laurolonate, 448 
Calcium mesitylenate, 123 
Calcium paraxylate, 125 
Calcium phenylacetate, 13 
Calcium phenylsuccinate, 325 
Calcium xylate, 124 
Camphanic acid, 446 
Camphene, 287, 411, 417, 428 
Camphene group, 417 
Camphene inactive, 410, 417 
Camphenes, 410 
Camphidene dichloride, 429 
Camphidene oxide, 433 
Camphimide, 438 
Camphineosazone, 435 
Camphidenoxime, 430 
Camphine oxide, 438 
Camphocarboxylic acid, 440 
Campholactone, 448 
Campholic acid, 419 
Camphol chloride, 442 
Campholenamide, 431 
Campholene nitril, 431 
Campholenic acid, 431 
Campholic acid, 441 
Camphonitril, 439 
Camphophenol, 433 
Camphophorine, 449 
Camphor, 424, 428, 431 
Camphor, addition products of, 439 
Camphoramie acid, 445 
Camphoramide, 445 
Camphor, artificial, 415 
Camphorates, 443 
Camphor boronfluoride, 439 
Camphor creosote, 295 
Camphor dichloride, 429 
Camphorethylimide, 446 
Camphorethylimidethylimidine, 446 
Camphorglucuronic acid, 428 
Camphorhydrazone, 432 
Camphorhydriodide, 439 
Camphoric acid, 442 
Camphorimide, 445 
Camphor, isomerides and homologues 
of, 474 
Camphor nitrate, 439 
Camphor of cubebs, 477 
Camphor of oil of lemons, 460 
Camphorogenol, 425 
Camphorol, 428 
Camphoronic acid, 448. 
Camphor, oxidation products of, 441 


Camphoroxime, 430, 431 

Camphoroxime anhydride, 430, 431 

Camphoroxime hydrochloride, 430 

Camphors, compounds related to the, 
469 


Camphoryl chloride, 445 
Camphoryl oxide, 444 
Camphylamine, 424, 432 
Caoutchouc, 485 ef seq. 
Carbostyril, 223, 225 
Carbostyril group, 223 
Carotin, 407 

Carvacrol, 295, 296 
Carvacrotic acid, 348 
Carvacrylamine, 293 
Carvene, 295, 411 

Carveol, 453 

Carvol, 295, 296, 452 
Carvol hydrazone, 453 
Carvoxime, 452 

Carvyl alcohol, 453 
Carvylamine, 453 
Caulosterin, 407 

Cedar camphor, 477 
Cetylbenzene, 397 
Cetylphenol, 397 
Chamomile, oil of, 475 
Chamomillol, 475 
Chloramethol, 196 
Chlorethylbenzene, 5 
a-Chlorhydratropic acid, 176 
Chlorisatic acid, 78 
Chlorisatin, 78 

Chlorisatoic acid, 98 
Chloroacetylbenzol, 61 
a-Chloro-8-bromothymoquinone, 299 
8-Chloro-a-bromothymoquinone, 299 
Chlorocamphocarboxylic acid, 440 
Chlorocamphor, 433 
B-Chloro-carbostyril, 227 
-Chlorocarbostyril, 228 
Chlorocinnamic acids, 217 
a-Chlorocinnamie acid, 235 
8-Chlorocinnamic acid, 236 
a-Chlorocoumarin, 245 
B-Chlorocoumarin, 246 
Chloroctylbenzene, 395 
Chlorodioxindol, 55 
Chlorohydrocinnamic acids, 166 
8-Chlorohydropiic acid, 177 
8-Chloromesitylenic acid, 126 
a-Chlorothymoquinone, 299 
B-Chlorothymoquinone, 299 
Chlorotrimesic acid, 142 
Chloroxindol chloride, 23 
Cholesterin, 402 

Cholesteryl acetate, 404 
Cholestery] alcohol, 402 
Cholesterylamine, 405 
Cholesteryl benzoate, 405 
Cholesteryl butyrate, 404 
Cholesteryl chloride, 404 
Cholesterylene, 404 
Cholesteryl stearate, 404 





INDEX. 


507 





Cinchol, 400 

Cinchyl acetate, 401 

Cinchyl alcohol, 400 

Cinene, 455 

Cineol 458 

Cinnamaldehyde, 206 

Cinnamaldoxime, 209 

Cinnamamide, 216 

Cinnamates, the, 215 

Cinnamein, 216 

Cinnamene, 27 

Cinnamenylacrylic acid, 369 

Cinnamenylcrotonic acid, 393 

Cinnamenylpropionic acid, 366 

Cinnamic acid, 207, 211; properties, 
214 ; hydrazine derivatives of, 230 

Cinnamic anhydride, 216 

Cinnamidene-aniline, 209 

Cinnamidenediamine, 208 

Cinnamidenephenylhydrazone, 209 

Cinnamocarboxylic acid, 316 

Cinnamol, 27 

Cinnamomin, 27 

Cinnamon, 206 

Cinnamonitril, 217 

Cinnamy! chloride, 216 

Cinnamylformamide, 337 

Cinnamylformic acid, 337 

Cinnamylformonitril, 337 

Cinnamyl hydride, 207 

Cinnamyl oxide, 216 

Cinnylamine, 204 

Cinnyl chloride, 204 

Cinnyl cinnamate, 216 

Cinnyl ethyl ether, 204 

Cinnyl iodide, 204 

Citrene, 411, 451 

Citronella oil, 471 

Citronellol, 471 

Colophene, 479 

Colophonia, 483 

Colophony, 482 

Compounds containing more than 
twelve atoms of carbon, 394 

Coniferin, 205 

Coniferyl alcohol, 205 

Conimene, 477 

Coorongite, 498 

Copaivaene, 479 

Copaivic acid, 483 

Copper benzoylacetone, 323 

Copper dichlorisatate, 79 

Copper phenylhydroxyacetate, 45 

Copper phenylpropiolate, 260 

Copper tyrasine, 182 

Coriandrol, 473 

Coriandryl acetate, 473 

Coriandryl chloride, 473 

Coriandry] iodide, 473 

Coumaraleohol, 239 

Coumaraldehyde, 239 

Coumarates, the, 240 

Coumaric acid, 240 

Coumarilic acid, 246, 247 


Coumarin, 241 
Coumarincarboxylic acid, 339 
Coumarin-melilotic acid, 244 
Coumarinphenylhydrazone, 245 
Coumarin, substitution products of, 245 
Coumarins, C,,H,O,, 368 
Coumaron, 247 

Coumaron dibromide, 247 
Coumaroxime, 245 
Coumaroxime ethyl ether, 245 
Cubebene, 476 

Cubebenylene bromide, 477 
Cubebenylene chloride, 476 


Cubebenylene iodide, 477 


Cubebin, 206 

Cumene, 153 

Cumene group, 102 

Cumene-orthosulphamide, 156 

Cumene-orthosulphonie acid, 155 

Cumeneparasulphamide, 155 

Cumeneparasulphonic acid, 155 

Cumenylacrylic acid, 389 

Cumenylbromopropionic acid, 383 

Cumenylpropionic acid, 383 

Cumic acid, 277 

Cumidenedichlorochromic acid, 312 

a-Cumidic acid, 279 

B-Cumidie acid, 280 

Cumidine, 157 

Cumin alcohol, 303 

Cuminaldehyde, 304 

Cuminaldoxime, 305 

Cuminamide, 306 

Cumin ether, 304 

Cuminic anhydride, 306 

Cuminol, 287, 304 

Cuminuric acid, 307 

Cumol, 102 

Cumol from coal tar, 103 

Cumonitril, 307 

Cumostyril, 390 

Cumoyl chloride, 306 

Cumoylic acid, 164 

Cupreol, 401 

Cupreyl acetate, 401 

Cupreyl alcohol, 401 

Cuprous phenylacetylene, 100 

Cyanacetophenone, 187 

Cyanbenzine, 15 

Cyanbenzoyl, 67 

Cyanocamphor, 439 

Cymene, 272, 287, 289 

Cymene, addition products of, 291 

Cymenecarboxylic acid, 347 

Cymene group, 272 

Cymene, halogen substitution products 
of, 291 

Cymenemetasulphonic acid, 292 

Cymene-orthosulphonic acid, 292 

Cymenol, 302 

Cymenotic acid, 348 

Cymenyl benzoate, 303 

Cymenyl methyl ether, 303 

Cymidine, 293 


508 


Cymol, 102 

Cymophenol, 296 
Cymophenol acetate, 297 
Cymopheny]l ethyl ether, 297 
Cymopheny] methyl ether, 297 
Cymophenyl phosphate, 297 
Cymyl acetate, 304 

Cymyl alcohol, 303 
Cymylamine, 304 

Cymyl chloride, 291, 303 
Cymyl compounds, 303 
Cymyl ethyl ether, 303 
Cymyl! mustard oil, 304 
Cynanchin, 399 
Cynanchocerin, 899 
Cynanchol, 399 

Cynene, 455 

Cynurin, 225 

Cynurenic acid, 225 


D. 

DAMMAR resin, 498 
Dammaryl, 498 
Daphnetin, 254 
Daphnin, 256 
Daucosterin, 407 
Dehydro-acetophenone-acetonecarboxy- 

lic acid, 385 
Dehydro-camphor, 438 
Dextropimaric acid, 481 
Dextropimaryl chloride, 481 
Dextropinene, 415 
Diacetylesculetin, 258 
Diacetylceatfeic acid, 251 
Diacety]daphnetin, 256 
Diacetylpyroguaiacin, 485 
Di-allyltoluene, 314 
Diamidocymene hydrochloride, 301 
Diamidoduric acid, 278 
Diamido-isobutylbenzene, 319 
Diamidomesitylene, 118 
Diamidothymoquinone, 300 
a-Diamidopseudocumene, 119 
y-Diamidopseudocumene, 121 
Di-amylbenzene, 396 
Diazo-isatoxime chloride, 93 
Dibasic acids, 324, 338, 361, 386; and 

their derivatives, 312; unsaturated, 

391 
Dibenzoylstyceric acid, 191 
Dibornyl ether, 422, 423 
Dibromacetophenone, 63 
Dibromatrolactic acid, 176 
Dibromdioxindol, 55 
D:ibromethylbenzene, 5 
Dibromindazol, 64 
Dibromisatic acid, 80 
Dibromisatin, 80 
Dibromisato-ethyloxime, 93 
Dibromisatoic acid, 98 
Dibromisatoxime, 93 
Dibromisodurene, 275 
Dibromocamphor, 435 
a-Dibromocamphor, 436 


INDEX. 





B-Dibromocamphor, 436 
a-Dibromocoumarin, 246 
B Dibromocoumarin, 246 
Dibromodurene, 274 
Dibromohydratropic acid, 194 
Dibromomesitylene, 108 
Dibromometa-isocymene, 302 
Dibromoparadipropylbenzene, 382 
Dibromopiperhydronic acid, 367 
Dibromopiperinide, 371 
Dibromoprehnitene, 277 
Dibromopseudocumene, 109 
Dibromotetra-ethylbenzene, 395 
Dicarvacrylamine, 293 
Dichlorisatic acid, 79 
Dichlorisatin, 79 
Dichlorisatoic acid, 98 
Dichlorocamphor, 434 
Dichlorodioxindol, 55 
Dichloromesitylene, 107 
a-y-Dichloroquionoline, 228 
Dicinnyl ether, 204 
Dicymyl ether, 304 
Diethoxycoumarilic acid, 257 
Diethylsculetin, 257 
Diethylbenzenes, 286 
Diethylbenzoic acid, 346 
Diethyl benzylmalonorthocarboxylate, 
366 
Diethyldaphnetilic acid, 255 
Diethyldaphnetin, 255 
Diethyl hydroxytrimesic acid, 142 
Diethylindigo, 94 
Diethyl isatoximate, 92 
Diethylmonobromesculetin, 257 
Diethylorthamidocinnamic acid, 221 
Diethylphenylmethane, 352 
w-Diethyltoluene, 352 
Dihydrocolophene, 481 
Dihydroxy-acids C,,H,,0, 356 
Dihydroxybenzenetetracarboxylic acids, 
283 
Dihydroxycamphene, 437 
B-y-Dihydroxycarbostyril, 229 
Dihydroxyduric acid, 278 
a-Dihydroxy-8-methylcoumarin, 335 
v-Dihydroxy-8-methylcoumarin, 335 
Dihydroxymethylcumarilic acid, 335 
a-8-Dihydroxyquinoline, 227 
a-y-Dihydroxyquinoline, 228 
Dihydroxyphenylacetic acids, 25 
Dihydroxyphenylacrylic acids, 249 
Dihydroxyphenylcrotonic acids, 332 
Dihydroxyphenylpropionic acids, 174 
a-8-Dihydroxypiperhydronic acid, 356 
B-y-Dihydroxypiperhydronic acid, 356 
Dihydroxypyromellitic acid, 283 
Di-indogen, 42 
Di-isopropene, 455 
Di-isopropylbenzene, 382 
Di-isopropylmetacresol, 394 
Diketones C,,H,,0,, 357 
Dimethoxyphenylpropionic acid, 253 
Dimethylesculetin, 257 


INDEX. 


Dimethylamidopentamethylbenzene, 
344 


Dimethylamidothymoquinone, 299 
Dimethylbenzenecarboxylic acids, 122; 
the substitution products of the, 126 
Dimethylbenzenedicarboxylic acids, 279 
Dimethylbenzoylacetic acid, 359 
Dimethyleaffeic acid, 251 
B-Dimethyl coumarate, 243 
Dimethylcoumarilic acid, 368 
Dimethylcoumarin, 368 
Dimethyl coumarinate, 243 
Dimethyldihydroxybenzenecarboxylic 
acias, 131 ; 
Dimethylethylbenzenes, 284 
Dimethylethylphenylmethane, 353 
Dimethylhomocaffeic acid, 333 
Dimethylhomophthalic acid, 361 
Dimethylhomophthalimide, 151 
Dimethylhydrocaffeic acid, 174 
Dimethylhydroxy benzenecarboxylic 
acids, 130 
Dimethylindol, 268 
Pr 1", 2-Dimethylindol, 269 
B3-Pr 2-Dimethylindol, 340 
Pr2-3-Dimethylindol, 340 
Pr1"-2-3-Dimethylindolacetic acid, 372 
Pr1®-2-3-Dimethylindolearboxylic acid, 
341 
Dimethylfumaric anhydride, 414 
Dimethyl-8-methylumbellic acid, 334 
Dimethylmesidine, 117 
Dimethylparamido-acetophenone, 59 
Dimethylpropylbenzenes, 346 
s-Dimethylpropylbenzene, 346 
Dimethylpseudocumidine, 119 
Dimethylthymoquinol, 298 
a-Dimethylumbellic acid, 253 
B-Dimethylumbellic acid, 253 
Dimethylumbelliferon, 369 
y-Dinitro-acetcumidide, 121 
Dinitro-acetmesidide, 118 
Dinitrocholesterin, 405 
a-3-Dinitrocinnamic acid, 238 
a-4-Dinitrocinnamie acid, 238 
Dinitrocyandibenzy], 18 
Dinitrodurene, 274 
Dinitroduric acid, 278 
Dinitrohydrocinnamic acid, 167 
Dinitro-isodurene, 276 
Dinitromesidine, 118 
Dinitromesitylene, 109 
Dinitromethylethylbenzenes, 144 
Dinitroparadipropylbeuzene, 382 
Dinitrophenylacetic acid, 19 
Dinitroprehnitene, 277 
Dinitropseudocumenol, 115 
a-Dinitropseudocumidine, 120 
y-Dinitropseudocumidine, 121 
Dinitropyromellitic acid, 281 
w-4-Dinitrostyrol, 35 
w-3-Dinitrostyrolene, 36 
Dinitrotetra-ethylbenzene, 395 
Dinitrotyrosine, 182 


509 


Di-orthohydroxyuvitic acid, 136 
Dioxindol, 21, 52 

Dioxindol hydrochloride, 53 
Dioxindol substitution products, 55 
Dioxindol sulphate, 53 
Dipentene, 411, 455, 464 
Dipentene group, 455 
Dipentene tetrabromide, 456 
Dipentenyl acetate, 463 
Dipentenyl alcohol, 461 
Dipentenylene bromide, 461 
Dipentenylene chloride, 460 
Dipentenylene glycol, 457 
Dipentenylene iodide, 461 
Dipentenyl oxide, 458 
Dipentenyl phenylcarbamate, 463 
Diphenylbutylene, 29 
Diphenyldiacetylene, 100 
Diphenyldi-iso-indol, 64 
Diphenylethylpropylene, 354 
Dipropylbenzenes, 382 
Dipropylmetacresol, 394 
Distyrenic acid, 217 
Distyrolene, 29 

Distyrolene bromide, 29 
Distyrolene dioxide, 30 
Distyrolylamine, 7 

Diterpenes, Cy)H3o, 479 
Dithio-isatyde, 96 
Dithymylamine, 293 
Dithymy] carbonate, 295 
Ditolyloxindol, 87 
Divalerylene, 455 

Draconyl, 28 

Durene, 272, 273 
Durenesulphonic acid, 274 
Durenesulphonic chloride, 275 
Durenol, 275 
Durenosulphamide, 275 

Duric acid, 277 

Duronitril, 277 

Duroquinone, 275 
a-Durylglyoxylic acid, 384 
s-Durylglyoxylic acid, 384 
a-Durylhydroxyacetic acid, 384 
s-Durylhydroxyacetic acid, 384 
a-Durylmethylearbinol, 384 
s-Durylmethylcarbinol, 384 
a-Durylmethylketone, 384 
s-Durylmethylketone, 384 


E. 


East Indian caoutchoue, 488 

Ethenylbenzene, 26, 100 

Ethenyldiamidopseudocumene, 119 

Ethers of isatin and the bromisatins, 
81 

Ethers of phenyldibromopropionic acid, 
192 

Ethoxycarbostyril, 227 

Ethoxyphenyldibromopropionic acid, 
244 


510 


INDEX. 





Ethylesculetin, 257 

Ethylamidohydrocarbostyril, 170 

Ethylatrolactic acid, 175 

Ethyl benzalmalonate, 338 

Ethylbenzene, 8 

Ethylbenzenecarboxylic acids, 146 

Ethylbenzenesulphonic acid, 6 

Ethyl benzoylacetate, 186 

Ethylbenzoylacetic acid, 359 

Ethyl benzoylformate, 69 

Ethyl-benzoy]-pyroracemate, 324 

Ethylbenzylketone, 320 

Ethyl bornyl ether, 422 

Ethylbromisatin, 81 

Ethylbromisatoid, 81 

Ethylbromisindazol, 66 

Ethylbromisindazolacetic acid, 232 

Ethylbromisindazolcarboxylic acid, 232 

Ethyl camphanate, 447 

Ethyl camphophenate, 433 

Ethylcamphene, 429 

Ethyl camphocarboxylate, 440 

Ethyleamphor, 433 

Ethyl camphoroximate, 430 

Ethylearbostyril, 224 

Ethyl cinnamate, 215 

a-Ethyleoumaric acid, 243 

B-Ethylcoumaric acid, 244 

Ethyleoumarin, 368 

Ethylcoumarinic acid, 248 

Ethyl cuminate, 306 

Ethyl dextropimarate, 481 

Ethyl diamidopyromellitate, 281 

Ethyl dibenzoylstycerate, 191 

Ethyl dibromisatate, §2 

Ethyl dibromisatin, 82 

Ethyl diketohexmethylenetetracarbox- 
ylate, 283 

Ethyl dihydroxydihydropyromellitate, 
283 


Ethyl dihydroxypyromellitate, 283 

Ethyl dinitropyromellitate, 281 

Ethylene-eugenol, 199 

Ethyl ethylcoumarate, 244 

Ethyl ethylcoumarinate, 244 

Ethyl eugenol, 198 

Ethylhydrocarbazostyril, 170, 352 

a-Ethylhydrocarbostyril, 169 

B-Ethylhydrocarbostyril, 169 

Ethyl hydrocinnamate, 165 

Ethyl hydroparacumarate, 173 

es cad aed acid, 
14 

Ethyl hydroxytrimesate, 142 

Ethylindazol, 65 

Ethylindol, 39 

Pr3-Ethylindol, 340 

Ethylindolearboxylic acid, 270 

Ethylindoxyl, 40, 41 

Ethyl indoxylate, 263 

Ethylindoxylie acid, 263 

Ethylisatic acid, 84 

Ethylisato-ethyloxime, 92 

Ethyl isatogenate, 262 


Ethyl isatoximate, 92 

Ethylisindazolacetic acid, 232 

Ethyl isonitrosobenzoylacetate, 187 

Ethyl isonitrosonitrophenylacetate, 20 

Ethyl isonitrosophenylacetate, 70 

Ethyl mellitate, 379 

Ethyl mesitylenate, 124 

Ethyl metanitrocinnamate, 219 

Ethyl metanitrophenylhydroxyacetate, 
52 


a-Ethylmetaxylene, 272 
a-Ethylmetaxylene, 284 
s-Ethylmetaxylene, 272, 284 
a-Ethylmetaxylenesulphamide, 285 
Ethylmethindazol, 66 
Ethylmethisindazol, 67 
Ethyl methylparacoumarate, 248 
Ethyl nitrobenzoylacetate, 187 
Ethyl-nitroso-indoxanthate, 264 
Ethylnitroso-indoxylic acid, 263 
Ethylorthamido-acetophenone, 58 
Ethyl orthamidocinnamate, 221 
Ethyl orthamidocinnamic acid, 221 
Ethylorthonitrocinnamate, 219 
Ethyl] orthonitrophenylpropiolate, 261 
a-Ethylorthoxylene, 272 
a-Ethylorthoxylene, 284 
a-Ethylorthoxylenesulphamide, 285 
Ethyloxindol, 22 
Ethyl paranitrophenylethoxynitropro- 
pionate, 238 
Ethyl _paranitrophenylunitro-acrylate, 
238 


Ethyl paranitrophenylpropiolate, 262 
Ethylparamethylpseudo-isatin, $0 
Ethyl paranitrocinnamate, 220 
Ethyl paranitrophenylacetate, 18 
Ethylparatolindol, 39 
Ethylparaxylene, 272, 284 
Ethylparaxylenesulphamide, 285 
Ethyl paraxylylenedimalonate, 387 
a-Ethylphenol, 4 

B-Ethylphenol, 4 

Ethyl phenylacetate, 13 
Ethylphenylacetylene, 239 
Ethylphenylcarbinol, 161 

Ethyl phenyldibromopropionate, 192 
Ethyl phenyldichloracetate, 71 
Ethylphenylformic acids, 146 

Ethyl phenylhydroxyacetate, 45 
Ethylphenylketone, 161 ~ 
a-Ethyl-8-phenylpropionie acid, 352 
Ethyl phenylpropyl ether, 160 
Ethylphenylvinyl acetate, 339 
Ethylphenylvinyl alcohol, 339 
Ethylphenylvinyl bromide, 339 
Ethyl] phloroglucinoltricarboxylate, 143 
Ethyl piperate, 371 
Ethylpseudo-isatin, 84 
Ethylpseudo-isatin-a-ethyloxime, 94 
Ethylpseudo-isatin-8-oxime, 95 
Ethylpseudoparatolisatin, 90 

Ethyl pyromellitate, 281 
Ethyltoluene, 144 


INDEX, 


511 





Ethyltolu-isatin, 86 - 
Ethyltolylparamethylimesatin, 89 
Ethyl trimesate, 139 

Eucalyptol, 459 

Eucalyptus, oil of, 417 
Euchronic acid, 379, 380 
Eugenic acid, 197 

Eugenol, 197, 200, 201 © 
Eugenolglycolic acid, 199 
Eugetinic acid, 315 


F. 


FERULAIC acid, 250 
Ferulaldehyde, 250 
Fichtelite, 499 
Fir-wood oi}, 416 
Fluocinnamic acid, 218 


G. 


GALIPOT, 480 

Gallacetophenone, 60 

Geranium oil; Indian, 471; Turkish, 
472; German, 7d. 

Geranoil, 472 

Geranyl bromide, 472 

Geranyl chloride, 472 

Geranyl ether, 472 

Geranyl iodide, 472 

Geranyl sulphide, 472 

German oil of geranium, 472 

Ginger grass oil, 471 

Glucocoumaraldehyde, 239 

Glucoferulaldehyde, 250 

Glucomandelic acid, 51 

Glucomethylcoumarylketone, 336 

Glucophenylhydroxyacetonitril, 49 

Glycyphillin, 172 

Guaiacic acid, 483 

Guaiene, 485 

Guaienequionone, 485 

Gurjunol, 480 

Guttapercha, 496 


H. 


HALOGEN derivatives of cinnamic acid, 
217 


Halogen substitution products of 
cymene, 291 
Halogen substitution products of 


hydrocinnamic acid, 166 
Halogen substitution products of 
phenylacetic acid, 15 
Halogen substitution products of the 
trimethylbenzenes, 107 
Hartite, 499 
Helenite, 498 
Hemellithene, 106 
Hemellithenesulphamide, 113 
Hemellithenesulphonic acid, 113 
Hemellithenol, 115 
Hemellithic acid, 126, 140 
Heptacetylamygdalin, 51 


Heptylbenzene, 394 

Hesperetin, 251 

Hesperetol, 32 

Hesperidene, 411, 451 

Hesperidin, 251 

Heveene, 480 

Hexbromomellitene, 374 

Hexchloromellitene, 374 

Hexethylbenzene, 396 

Hexhydrocumene, 106 

Hexhydrocymene, 291 

Hexhydromesitylene, 104 

Hexmethylbenzene, 373 

Hexyleugenol, 199 

Homocuminic acid, 350 

Homoferulic acid, 332 

Homohydroxyisophthalie acid, 137 

Homologues of camphor, 474 

Homomethylumbelliferon, 369 

Homo-orthophthalamic acid, 152 

Homo-orthophthalic acid, 150 

Homo-orthophthalonitril, 152 

Homophthalic acids, 150 

Homophthalie anhydride, 151 

Homophthalimide, 151 

Homophthalmethylimide, 151 

Homoterephthalic acid, 152 

Homotoluic acid, 164 

Homo-umbelliferon, 314 

Honeystone, 379 

Honeystone acid, 374 

Hydratropic acid, 162 

Hydrazine derivatives of cinnamic acid, 
230 

Hydrazinhydrocinnamic anhydride, 169 

Hydrazopseudocumene, 110 

Hydridinie acid, 52 

Hydrindonaphthenedicarboxylie acid, 
363 

Hydrindonaphthenemonocarboxylic 
acid, 363 

Hydro-acetophenonecarboxylic 
149 

Hydro-esculetin, 256 

Hydrocaffeic acid, 174 

Hydrocarbons of the formula C,H;. 
C,H;, 339 

Hydrocarbons of the formula C,,H,,, 
343, 

Hydrocarbons of the formula C,,H,,_., 
402 

Hydrocarbons C,,H,,4 and their deriva- 
tives, 353 

Hydrocarbons C,,H,, and their deriva- 
tives, 373 

Hydrocarbons C,.H,, and their deriva- 
tives, 389 

Hydrocarbons CyHon_j9 and their deri- 
vatives, 393 

Hydrocarbons CyHon_g and their deri- 
vatives, 394 

Hydrocarbostyril, 168, 169 

Hydrocarotin, 407 

Hydrochelosterylene, 404 


acid, 


512 INDEX, 


Hydrochloride of benzoyl acetimido- 
ether, 188 
Hydrochloride of oil of lemons, 460 
Hydrochlorocarvol, 453 
Hydrochlorocarvoxime, 453 
Hydrocinnamice acid, 164 
Hydrocinnamide, 208 
Hydrocinnamonitril, 166 
Hydrocinnamorthocarboxylic acid, 312 
Hydrocoumaric acid, 173 
Hydrocoumarilic acid, 247 
Hydrocoumaroxime, 245 
Hydroferulic acid, 174 
Hydrohomoferulic acid, 333 
Hydromellitic acid, 380 
Hydromethylketol, 268 
Hydroparacumaric acid, 172 
a-Hydropiperic acid, 367 
B-Hydropiperic acid, 367 
Hydroprehnitic acid, 283 
Hydropyromellitic acid, 281 
Hydroskatol, 266 
Hydro-umbellic acid, 175 
Hydroxy-acids C,,H,,03, 354 
Hydroxy benzene-aldehydo-dicarboxylic 
acids, 141 
Hydroxybenzenetricarboxylic acids, 141 
Hydroxycamphor, 430, 431 
a-Hydroxycarbostyril, 227 
B-Hydroxycarbostyril, 227 
+-Hydroxycarbostyril, 228 
Hydroxycoumarins, C,,H,,.03, 369 
Hydroxycuminic acid, 309 
Hydroxyduric acid, 278 
Hydroxyhydrocarbostyril, 183 
Hydroxyisocamphor, 438 
Hydroxyisopropylbenzenesulphonic 
acid, 155 
Hydroxyisopropylbenzoic acid, 310 
Hydroxyisopropylmetamidobenzoic 
acid, 311 
Hydroxyisopropylmetanitrobenzoic 
acid, 311 
Hydroxyisopropylorthamidobenzoic 
acid, 311 
Hydroxyisopropylorthonitrobenzoic 
acid, 311 
Hydroxyisopropylsalicylic acid, 311 
Hydroxyisopropylsulphobenzoic acid, 
310 


a-Hydroxymesitylenic acid, 130 
B-Hydroxymesitylenic acid, 130 
Hydroxyparaxylic acid, 131 
Hydroxyphenylacetic acids, 23 
Hydroxyphenylacrylaldehyde, 239 
Hydroxyphenylacrylic acids, 240 
Hydroxyphenylerotonic acids, 331 
Hydroxyphenylpropionic acids, 170 
Hydroxypiperhydrolactone, 356 
Hydroxypiperhydronie acid, 355 
Hydroxypipitzahoie acid, 398 
Hydroxypropylbenzoic acids, 310 
Hydroxyquinoline, 225 
Hydroxythymoquinone, 299 


Hydroxythymoquinoneanilide, 300 
Hydroxytrimellithic acid, 143 
Hydroxytrimesic acid, 141 
Hydroxyxylidic acid, 137 
Hyoscyamine, 177 

Hypnone, 57 


I 


IDOLCARBOXYLIC acid, 270 

Ilicyl acetate, 402 

Tlicyl alcohol, 401 

Ilicyli alcohol, 402 

Imesatin, 87 

Imido-compounds of mellityl, 379 

Indazol, 64, 65 

Indazol group, 64 

Indazolacetic acid, 66, 231 

Indian melissa oil, 471 

Indian oil of geranium, 471 

Indic acid, 97 

Indigo-blue sulphuric acid, 82 

Indigotindisulphonic acid, 82 

Indin, 96 

Indogen, 42 

Indogenide of benzaldehyde, 42 

Indogenide of pyroracemic acid, 42 

Indogenides, the 42 

Indol, 37 

Indolcarboxylic acids containing ten 
carbon atoms, 341 

Indol derivatives containing eleven 
atoms of carbon, 372 

Indoldicarboxylic acid, 342 

Indol picrate, 38 

Indols, substituted, 264 

Indols C,,)H,,N, 340 

Indophenin, 77 

Indoxanthic acid, 263 

Indoxyl, 40, 41 

Indoxylic acid, 40, 41, 262 

Indoxylsulphuric acid, 40, 41 

Iodo-camphor, 436 

Iodo-cinnamic acids, 218 

Iodohydrocinnamic acids, 167 

Tsanethol, 197 

Isatic acid, 73, 77 

Isatin, 21, 73, 74 

Isatin chloride, 83 

Isatindiamide, 87 

Isatindiamide hydrochloride, 87 

Isatindiamide sulphate, 87 

Isatinoxime, 91 

Isatinsulphonic acid, 82 

Isatinsulphuric acid, 82 

Isatinosulphurous acid, 77 

Isatis tinctoria, 73 

Isato-ethyloxime, 92 

Isatogenic acid, 262 

Isatoic acid, 97 ; substitution products 
of, 97 

Isatoxime, 91 

Isatropic acid, 234 


i te 


INDEX. 


513 





a-Isatropic acid, 234 
B-Isatropic acid, 234 
Isatydt, 95 
Isobutenylstyrolene, 393 
a-Isobutybenzene, 272, 318 
B-Isobutyhenzene, 272, 319 
Isobutyleamphene, 429 
Isobutyleugenol, 199 
Isobutylorthocresol, 349 
a-Isobutylorthotoluidine, 349 
v-Isobutylorthotoluidine, 349 
a-Isobutylpara-iodobenzene, 319 
Isobutylparamidobenzene, 319 
Isobutylphenol, 319 
Isobutyl phenylacetate, 13 
Isocamphoroxime, 430, 431 
Isocholesterin, 405 
Isocholesteryl benzoate, 405 
Isocumidic acid, 280 
Isocumol, 103 
Isodurene, 272, 275 
Isodurenol, 276 
a-Isoduric acid, 279 
B-Isoduric acid, 279 
y-Isoduric acid, 279 
Isoduridine, 276 
Iso-eugenol, 199, 200 
Isohexylbenzene, 383 
Isohydroferulic acid, 174 
Isohydromellitic acid, 381 
Isohydropyromellitic acid, 282 
Iso-indileucin, 63 
Iso-indol, 63 
Isomerides and homologues of camphor, 
474 
Isomerides of borneol, 471 
Isonitrosobenzoylacetone, 323 
Isonitrosophenylacetic acid, 70 
Isonitrosopinene, 415 
Isophenylcrotonic acid, 329 
Isoprene, 491 
Isopropenylbenzoic acid, 315 
Isopropylbenzene or cumene, 103, 153 
Isopropylbutenylbenzene, 402 
B-lsopropylbutenylbenzene, 402 
Tsopropylcarballylic acid, 449 
Isopropylcoumarin, 391 
Isopropyleugenol, 199 
Isopropylphenylbutylene, 402 
Isopropylphenylbutenyl bromide, 402 
Isopropylphenylisobutylene, 402 
Isopropylphenylketone, 320 
Isopropylphenylpropylene, 389 
Isoterebentene, 455 
Isoxylamide, 126 
Isoxylic acid, 125 
Isoxylidic acid, 136 
Tsuritic acid, 150 
Juniper, oil of, 416 


K. 


KETOMIC acids, 185 


Ketones, 161 

Ketones, C,, H,, O, 357 
Ketones and ketonic acids, 384 
Ketonic acids, 148, 322, 337, 358 


Ee 


LACTUCERIN, 399 

Lactucerol, 399 

a-Lactucerol, 399 
B-Lactucerol, 400 

a-Lactuceryl acetate, 400 
B-Lactuceryl acetate, 400 
Lactuceryl alcohol, 399 
Levoborneol, 420 
Levomandelic acid, 44 
Levopinene, 414, 425 
Levopimaric acid, 481 

Lapis cancrorum, 88 

Laurene, 346 

a-Laurene, 347 

B-Laurene, 347 

Laurene group, 343 
a-Laurenesulphonamide, 347 
a-Laurenesulphonie acid, 347 
Lauronolic acid, 448 

Lead chlorisatate, 78 

Lead phenylhydroxyacetate, 45 
Ledum camphor, 477 
Lemon-grass oil, 471 
Lemons, oil of, 451 
Lignum aloes, 473 
Limonene, 411, 450 
Limonene group, 450 
Limonene nitrosochloride, 452 
Limonene tetrabromide, 452 
Linaloes wood, 473 

Linaloeol, 472 


» 


M. 


Mace, oil of, 417 
Magnesium camphorate, 444 
Mandelic acid, aromatic substitution 
products of, 51 
Mandelic acid chloralide, 46 
Matico camphor, 475 
Meconinacetic acid, 313 
Melilotie acid, 173 
Melitolol, 174 
Mellite, 379 
Mellitene, 373 
Mellitene group, 373 
Mellitic acid, 374 
Mellitimide, 380 
Mellitiminic acid, 380 
Mellitone hexchloride, 374 
Mellitonic hexbromide, 374 
Mellityl chloride, 379 
Mellophanic acid, 282 
Menthene, 469, 471 
Menthol, 469, 471 


514 


INDEX. 





Menthone, 470 
Menthyl acetate, 470 
Menthyl alcohol, 469 
Menthyl bromide, 470 
Menthyl carbamate, 470 
Menthyl carbonate, 470 
Menthyl chloride, 470 
Menthyl iodide, 470 
Menthyl phenylcarbamate, 470 
Mesidic acid, 133 
Mesidine, 117 
Mesitene acetate, 132 
Mesitene alcohol, 132 
Mesitene bromide, 132 
Mesitene chloride, 132 
Mesitene compounds, 132 
Mesitenyl alcohol, 137 
Mesitenyl bromide, 138 
Mesitenyl chloride, 137 
Mesitenyl compounds, 137 
Mesitic alcohol, 102 
Mesitol, 114 
Mesityl acetate, 122 
Mesityl alcohol, 121 
Mesitylaldehyde, 123 
Mesityl bromide, 121 
Mesitylearbimide, 117 
Mesityl chloride, 121 
Mesityl compounds, 121 
Mesitylenamide, 124 
Mesitylene, 102, 103, 104 
Mesitylenedisulphonic acid, 112 
Mesityleneglycero!, 137 
Mesityleneglycol, 132 
Mesitylenesulphamide, 112 
Mesitylenesulphonic acid, 112 
Mesitylenesulphonic chloride, 112 
Mesitylenic acid, 122, 123 
Mesityl mustard oil, 117 
Mesitylurethane, 117 
Mesocamphoric acid, 446 
Mesorcinol, 116 
Meta-allyltoluene, 314 
Meta-amyltoluene, 382 
Metabromocymene, 291 
Metachlorocymene, 291 
Metacopaivic acid, 483 
Metacumophenol, 156 
Metacymene, 272, 301 
Metacymophenol, 294 
Metadiethylbenzene, 272 
Metadihydroxyacetophenone, 60 
Meta-eugenol, 199, 200 
Metahydroxycoumarin, 254 
Metahydroxycumenylacrylic acid, 390 
Metahydroxycuminie acid, 309 
Metahydroxymethylcoumarilic 
304 





acid, 


Metahydroxyphenylacetic acid, 24 
Metahydroxyphenylacetonitril, 24 
Metahydryoxyuvitic acid, 136 
Meta-isobutylbenzoic acid, 350 
Meta-isobutyltoluene, 348 
Meta-isobutyltoluenesulphamide, 349 


Meta-isocymene, 272, 301 
Meta-isocymenesulphonie acid, 302 
Meta-isocymidine, 303 
Meta-isocymophenol, 302 
Metamethylecaffeic acid, 250 
Metamethylcinnamic acid, 314 
Metamethylethylbenzene, 103, 144 
Metamethylmandelic acid, 148 
Metamethoxycoumarin, 254 
Metamethylphenylacetic acid, 147 
Metamethylpropylbenzene or metacy- 
mene, 272 
Metamido-acetophenone, 58 
Metamidobenzoylformie acid, 73 
Metamidocinnarie acid, 222 


- Metamidocumenylacrylic acid, 390 


Metamidocumenylpropionic acid, 383 
Metamidocuminic acid, 308 
Metamidocymene, 293 
Metamidohydrocinnamie acid, 168 
Metamidophenylacetic acid, 20 
Metamidophenylacetonitril, 21 
Metamidophenylamido-acetic acid, 52 
Metanethol, 196 
Metanitroacetamidophenylacetonitril, 
20 
Metanitro-acetophenone, 57 
Metanitrobenzoylformamide, 71 
Metanitrobenzoylmethylene bromide,63 
Metanitrocinnamaldehyde, 210 
Metanitrocinnamic acid, 219 
Metanitrocumenylacrylic acid, 390 
Metanitrocuminic acid, 307 
Metanitrocuminol, 305 
Metanitrobenzoylformic acid, 71 
Metanitrobenzoylformonitril, 71 
Metanitrohydrocinnamic acid, 167 
Metanitromendelic acid, 51 
Metanitro-octylbenzene, 395 
Metanitroparamidophenylacetic 
20 
Metanitrophenylacetic acid, 18 
Metanitrophenylacetonitril, 19 
Metanitrophenylamido-acetic acid, 52 
Metanitrophenylethoxydibromonitro- 
ethane, 36 
Metanitrophenylnitro-acrylic acid, 238 
Metanitrophenylnitro-ethylene, 36 
Metanitrostyrolene, 35 
Metaphenylenedi-acetic acid, 287 
Metaphenylenedipropionic acid, 387 
Metapropylmethylbenzene, 301 
Metastyrol, 27 
Metastyrolene, 29 
Metatolylmethylketone, 146 
Metatolylpropionic acid, 311 
Metaxylylenedichlorodimalonic 
387 
Metaxylyenedimalonic ether, 387 
Metaxylorcinolecarboxylic acid, 131 
Metaxylylglyoxylic acid, 285 
Methindazol, 64, 66 
Methisindazol, 64 
Methronene, 329 


acid, 


acid, 


INDEX. . 515 





Methylesculetin, 257 
Methylamidobenzoylacetocarboxylic 
acid, 317 
Methylamidopentamethylbenzene, 344 
Methylatropic acid, 330 
Methylbenzenedicarboxylic acids, 183 
Methyl benzoylformate, 69 
Methylbenzylacetic acid, 321 
Methylbenzylaceto-acetic acid, 384 
Methylbenzylcarbinol, 160 
Methylbenzylketone, 161 
Methylbenzylmalonic acid, 362 
Methyl bornyl ether, 422 
Methylbromisatin, 81 
Methylbromisatoid, 81 
Methyl-a-bromostyrolene, 148 
Methyl-8-bromostyrolene, 148 
Methylbutylbenzenes, 348 
Methylearbostyril, 224 
Methyl cinnamate, 215 
B-Methylcoumaramide, 243 
a-Methyleoumarie acid, 243 
8-Methylcoumarie acid, 243 
Methyleoumarilic acid, 332 
B-Methylcoumarin, 331 
Methylcoumarinic acid, 243 
Methylcoumarylketone, 336 
Methyl-a-cumidate, 280 
Methyl-8-cumidate, 280 
B-Methyldaphnetin, 335 
Methyldemethyleaffeate, 251 
Methyldibromostyrolylketone, 336 
S-Methyldiethylbenzene, 346 
s-Methyldipropylbenzene, 394 
Methylenedihydroxymandelic acid, 55 
Methylenedioxyphenylangelic acid, 368 
Methylenehydrocaffeic acid, 174 
Methylenephthalmethimidine, 317,318 
Methyl ether, 196 
Methylethylbenzenes, 144 
Pr2-3-Methylethylindol, 372 
Methylethylsalicylic acid, 285 
Methyleugenol, 198 
Methyleugetinie acid, 315 
Methylferuloketone, 337 
Methylhomoferulic acid, 333 
Methylhomophthalic acid, 312 
Methylhomophthalonitril, 312 
Methylhydrocinnamate, 165 
Methylhydroparacumaric acid, 173 
Methylhydroxy benzenedicarboxylic 
acids, 136 
Methylindol, 38 
Pr 1"-Methylindol, 269 
Pr 2-Methylindol, 269 
Pr 3-Methylindol, 269 
B3-Methylindol, 269 
Pr2-3-Methylindolacetic acid, 372 
Methylindolearboxylic acid, 270 
B1-Pr2- Methylindolearboxylic acid, 342 
B3-Pr2-Methylindolearboxylic acid,342 
Methylindol picrate, 39 
Methylisatin, 81 
Methylisatoid, 81 


Methyl] isohydromellitate, 381 
Methylisophthalic acid, 136 
Methylketol, 267, 269 
Methylketolazobenzene, 267 
Methylmandelic acid, 46 
Methylmelilotic acid, 174 
Methyl mellitate, 379 
Methylmethindazol, 66, 67 
Methyl methylparacoumarate, 248 
Methyl-8-methylumbellic acid, 334 
Methylorthotolindol, 39 
Methylparacoumarie acid, 248 
Methylparacoumaryl chloride, 248 
Methylparahydroxymandelic acid, 55 
Methylparahydroxyphenylacetic acid, 
24 


Methylparahydroxyphenylacetonitril, 
24 


Methyl paranitrophenylacetate, 17 
Methylparatolindol, 39 
Methyl] phenylacetate, 13 
Methylphenylacetic acids, 147 
Methylphenylearbinol, 8 
Methylphenylchloracetate, 46 
Methyl phenyldibromopropionate, 192 
Methyl phenylhydroxyacetate, 45 
Methylphenyl-hydroxyacetic acids, 148 
Methylphenylketone, 56 
a-Methylphthalide, 149 
Methylpropenylbenzene, 314 
Methylpropenylbenzene and its deriva- 
tives, 314 
a-Methylpropioncoumaric acid, 331 
B-Methylpropioncoumaric acid, 331 
Methylpropionparacoumaric acid, 331 
Methylpropylbenzenes, 287 
Methylpropylbenzoic acid, 347 
Methylpseudocumidine, 119 
Methylpseudo-isatin, 84 
Methylpseudoparatolisatin, 91 
Methylpseudorthotolisatin, 91 
Methyl pyromellitate, 281 
Methylresacetophenone, 60 
Methylstyrolene, 147 
Methylstyrolene bromide, 148 
Methylstyrolylcarbinol, 320 
Methylstyrolylketone, 320 
Methyltolylacetoxime, 146 
Methyltolylketonephenylhydrazine, 
146 
Methyl trimesate, 139 
B-Methylumbellic acid, 334 
Methylumbelliferon, 253 
B-Methylumbelliferon, 333 
Mochyl alcohol, 402 
Mochyllene, 402 
Monamido isatin, 88 
Monobromindazolacetie acid, 231 
Monobromindazolearboxylic acid, 231 
Monobromocamphene, 419 
Monobromomesitylene, 108 
a-Monobromopseudocumene, 108 
v-Monobromopseudocumene, 108 
s-Monobromopseudocumene, 108 


516 INDEX. 


Monochloromesitylene, 107 
Monochloropseudocumene, 108 
Mono-ethyldaphnetin, 255 
Mononitromesitylene, 109 
a-Mononitropseudocuniene, 110 
B-Mononitropseudocumene, 110 
y-Mononitropseudocumene, 110 
Myristicol, 474 


Ne 


NARINGENIN, 249 

Naringin, 249 

Ngai camphor, 420 
Nicrocetylbenzene, 397 
Nitramido-isobutylbenzene, 319 
+-Nitro-acetcumidide, 121 
Nitro-acetmesidide, 117 
Nitro-acetpseudocumide, 119 
Nitrobromisatin, 82 
Nitrobromocamphor, 437 
Nitrocamphor, 436 
a-Nitrocarbostyril, 225 
B-Nitrocarbostyril, 225 
y-Nitrocarbostyril, 225 
Nitrocarvacrol, 301 
Nitrochlorocamphor, 437 
Nitrocinnamic acids, 218 
a-Nitrocoumaraldehyde, 239 
B-Nitrocoumaraldehyde, 240 
Nitrocoumarin, 246 
Nitrocubebin, 206 
Nitrocumene, 156 
Nitrocumenyldibromopropionic acid, 
Nitrocumidine, 157 

Nitrocymene, 292 
Nitrodiamidomesitylene, 118 
Nitro-isatin, 82 

Nitro-isatoic acid, 98 

Nitromesidine, 117 c 
Nitromesitol, 114 

a-Nitromesitylenic acid, 127 
B-Nitromesitylenic acid, 127 
Nitrometa-isocymene, 303 
Nitro-8-methylumbelliferon, 333 
a-Nitro-orthamidocinnamic acid, 221 
B-Nitro-orthamidocinnamie acid, 222 
Nitro-oxindol, 22 
Nitroparamethylisatoic acid, 99 
Nitrophellandrene, 468 
Nitrophenylacetic acids, 16 
a-Nitrophenylbromacrylaldehyde, 210 
B-Nitrophenylbromacrylaldehyde, 211 
y-Nitrophenylbromacrylaldehyde, 211 
Nitrophenylethylenes, 35 
Nitrophenyl-lactyl nitrate, 183 
Nitro-pinene, 415 
Nitro-propiophenone, 161 
Nitropseudocumenequinol, 116 
Nitropseudocumenequinone, 116 
Nitro-a-pseudocumenol, 114 
Nitropseudocumenyl nitrate, 114 





a-Nitropseudocumidine, 119 

y- Nitropseudocumidine, 120 

Nitroresacetophenone, 60 

Nitroso-amido-8-methylumbelliferon, 
303 

Nitrosocarvacrol, 301 

Nitrosodioxindol, 54 

Nitrosohydromethylketol, 268 

Nitroso-y-hydroxycarbostyril, 229 

Nitroso-indazol, 65 

Nitroso-indoxy], 40, 42, 98 

Nitrosomethindazol, 66 

Nitroso-ortho-ethylamidocinnamic 
acid, 221 

Nitroso-oxindol, 74, 91 

Nitrosothymol, 300 

Nitrostyrol, 33 

Nitrostyrolenes, 35 

Nitrothymol, 300 

Nitrotrimethylbenzenes, 109 

Nitrotyrosine, 182 

Nitroxylic acid, 128 

a-Nitro-uvitic acid, 1385 

B-Nitro-uvitic acid, 135 

Normal ammonium mellitate, 379 

Normal barium trimesate, 139 

Normal calcium hydroxytrimesate, 142 

Normal ethyl camphorate, 444 

Normal potassium mellitate, 378 

Normal sodium trimesate, 139 

Normeconinacetic acid, 313 


0. 


OCTODECATYLBENZENE, 397 

Octodecatylphenol, 397 

Octylbenzene, 395 

Octylbenzoic acid, 396 

Octyltoluene, 396 

Oil of turpentine, 410, 412; juniper, 
416; sage, ibid. ; mace, 417 ; euca- 
lyptus, ibid. ; rosemary, ibid. ; 
lemon, 451; orange peel, zbid. ; 
bergamot, 7zbid.; turpentine cam- 
phor, 457; Indian melissa, 471; 
lemon-grass, zbid.; verbena, <bid ; 
citronella, zbid. ; Indian of geranium, 
ibid ; rusa, ibid. ; ginger grass, ibid. ; 
Turkish of geranium, 472 ; German 
of geranium, 7bid. ; chamomile, 475 

Olivil, 200 

Opianylacetic acid, 313 

Orange-peel, oil of, 451 

Orthamido-acetophenone, 58 

Orthamidobenzoylformic acid, 77 

Orthamidocinnamic acid, 220 

Orthamidocumenylacrylic acid, 390 

Orthamidocuminic acid, 308 

Orthamidocymene, 293 

Orthamido-ethylbenzene, 6 

Orthamidophenylacetylene, 101 

Orthamidophenylpropiolic acid, 262 

Orthamidophenylvinyl chloride, 36 


INDEX. 517 





Orthamidopropylcinnamic acid, 390 
Ortho-acetylbenzoic acid, 149 
Ortho-amidophenylacetic acid, 21 
Orthobromocumene, 154 
Orthobromocymene, 291 
Orthobromophenylacetic acid, 16 
Orthobromopropy] benzene, 158 
Orthochlorocymene, 291 
Orthocuminic acid, 308 
Orthocumophenol, 156 
Orthocyanobenzy1 chloride, 152 
Orthocymene, 272, 301 
Orthocymophenol, 295 
Ortho-ethylbenzenecarboxylic acid, 146 
Orthohydrazinecinnamic acid, 230 
Orthohydrazinecinnamic anhydride, 
230 
Orthohydroxybenzoylformic acid, 72 
Orthohydroxybenzylglycolic acid, 189 
Orthohydroxybenzylglyoxylic acid, 189 
Orthohydroxycoumarin, 254 
Orthohydroxycumenylacrylic acid, 390 
Orthohydroxycuminic acid, 309 
Orthohydroxymandelic acid, 55 
Orthohydroxyphenylacetic acid, 24 
Ortho-isobutenylphenol, 327 
Ortho-isopropylbenzoic acid, 308 
Ortho-isopropylphenylearboxylic acid, 
310 


Orthomethylethylbenzene, 103, 145 
Orthomethylphenylacetic acid, 147 
Orthomethylpropylbenzene or ortho- 
cymene, 272 
Orthonitro-acetophenone, 57 
Orthonitrobenzoylformamide, 72 
Orthonitrobenzoylformic acid, 72 
Orthonitrobenzoylformonitril, 72 
Orthonitrobenzoylmethyl bromide, 62 
Orthonitrobenzoylmethylene bromide, 
63 
Orthonitrocinnamaldehyde, 209 
Orthonitrocinnamic acid, 219 
Orthonitrocumenylacrylic acid, 389 
Orthonitrocuminic acid, 307 
Orthonitro-cuminol, 305 
Orthonitro-ethylbenzene, 6 
Orthonitrohydratropic acid, 163 
Orthonitrohydrocinnamic acid, 167 
Orthonitro-8-hydroxycinnamic acid, 
237 
Orthonitro-isopropylcinnamic acid, 389 
Orthonitro-octylbenzene, 395 
Orthonitroparamidophenylacetic acid, 
19 
Orthonitroparapropylbenzoic acid, 308 
Orthonitrophenylacetic acid, 18 
Orthonitrophenylacetonitril, 18 
Orthonitrophenylacetylene, 100 
Orthonitrophenylacrylaldehyde, 209 
Orthonitrophenylchlorethylene, 36 
Orthonitrophenylchloroactic acid, 192 
Orthonitrophenyldibromopropionic 
acid, 219 
Orthonitrophenylglycidic acid, 193 





Orthonitrophenylnitro-ethylene, 36 
Orthonitrophenylnitropylene, 195 
Orthonitrophenylpropiolic acid, 261 
Orthonitrophenylvinyl chloride, 36 
Orthonitropropyleinnamic acid, 390 
Orthonitrostyrolene, 35 
Orthophenylenedi-acetic acid, 286 
Orthophenylenedipropionic acid, 386 
Orthopropylbenzoic acid, 309 
Orthopropylmethylbenzene, 301 
Orthopropylphenolcarboxylic acid, 310 
Orthopropylphenol, 159 
Orthotribromacetylbenzoic acid, 149 
Orthotrichloracetylbenzoic acid, 149 
Orthovinylanisol, 31 
Orthoxylylene cyanide, 286 
Orthoxylylenedichlorodimalonic acid, 
386 


Orthoxylylenedimalonic acid, 386 
Orthoxylylglyoxylic acid, 286 
Oxidation products of camphor, 441 
Oxindol, 21 

Oxindol hydrochloride, 22 

Oxindol silver, 22 

Oxycumarin, 189 

Oxycymol, 296 
Oxydimidodiamido-isatin, 88 


Pr 


PAEONIA MUTAN, 60 

Paeonol, 60 

Para-acetylbenzoic acid, 148 

Para-amyltoluene, 382 

Parabromocumene, 154 

Parabromophenylacetic acid, 16 

Parabromophenylacetonitril, 16 

Parabromopropylbenzene, 158 

Para-a-butenylphenyl methyl 
326 

Paracamphoric acid, 446 

Para caoutchouc, 487 

Paracarvacrotic acid, 348 

Parachloracetophenone, 57 

Parachlorophenylacetic acid, 15 

Paracholesterin, 406 

Paracholesteryl benzoate, 407 

Paracota bark, volatile constituents of, 
478 

a-Paracotene, 478 

B-Paracotene, 479 

a-Paracotol, 479 

B-Paracotol, 479 

y-Paracotol, 479 

Paracoumarhydrin, 26 

Paracoumaric acid, 248 

Paracumophenol, 156 

Paracumopheny] ethyl ether, 156 

Paracumophenyl methyl] ether, 156 

Paradichlorethylbenzene, 5 

Paradiethylbenzene, 272, 286 

Paradihydroxyacetophenone, 59 

Paradipropylbenzene, 382 


ether, 


518 : INDEX. 





Paresculetin, 256 
Para-ethylbenzenecarboxylic acid, 146 
Parahydroxyacetophenone, 59 
Parahydroxyhydratropic acid, 171 
Parahydroxyhydrocinnamic acid, 172 
Parahydroxyphenylacetic acid, 23 
Parahydroxyphenylacetonitril, 24 
Parahydroxy-a-phenyl-lactic acid, 183 
Parahydroxystyrolylamine, 8 
Para-iodo-acetophenone, 57 
Para-iodo-capryl-benzene, 396 
Para-iodo-cumene, 155 
Para-iodo-octylbenzene, 395 
Para-iodophenylbenzoic acid, 16 
Para-iodopropylbenzene, 158 
Para-isobutenylphenol, 327 
Para-isobutylbenzoic acid, 350 
Para-isobutylbenzonitril, 350 
Para - isobutylorthohydroxybenzenecar- 
boxylic acid, 350 
Para-isobutyltoluene, 349 
Para-isobutyltoluenesulphamide, 350 
Para-isocymene, 272, 301 
Para-isopropylbenzoic acid, 305 
Para-isopropylmetastyrolene, 353 
Para-isopropyiphenolcarboxylic acid, 
310 


Para-isopropylstyrolene, 353 
Para-isopropylstyrolene bromide, 353 
Parallylanisoil, 196 
Paramethyleaffeic acid, 250 
Paramethylethylbenzene, 103, 144 
Paramethylimesatin, 89 
Paramethylisatin, 90 
Paramethylisatoic acid, 99 
Paramethylisatoxime, 93 
Paramethylmandelic acid, 148 
Paramethylphenylacetic acid, 147 
Paramethylpropylbenzene or cymene, 
272 


Paramide, 379, 380 
Paramidic acid, 380 
Paramido-acetophenone, 58 
Paramido-caprylbenzene, 396 
Paramidocinnamiec acid, 222 
Paramidocumene, 157 
Paramidoethylbenzene, 6 
Paramidohydratropic acid, 163 
Paramidohydrocarbostyril, 169 
Paramidohydrocinnamic acid, 167 
Paramidometanitrohy drocinnamic acid, 
168 
Paramido-octylbenzene, 396 
Paramido - orthonitrohydrocinnamic 
acid, 168 
Paramido-oxindol, 22 
Paramidophenylacetic acid, 19 
Paramidophenylacetonitril, 19 
Paramidophenylalanine, 179 
Paramidopropylbenzene, 159 
Paramido-a-phenyl-lactic acid, 183 
Paranitio-acetophenone, 58 
Paranitrobenzoiec acid, 35 
Paranitrobenzoylacetic acid, 187 


Paranitrocinnamaldehyde, 210 
Paranitrocinnamic acid, 220 
Paranitro-ethylbenzene, 6 
Paranitrohydratropie acid, 163 _ 
Paranitrohydrocinnamic acid, 167 
Paranitro-B-hydroxycinnamic acid, 238 
Paranitro-octylbenzene, 396 
Paranitrophenylacetaldehyde, 10 
Paranitrophenylacetic acid, 17 
Paranitrophenylacetonitril, 18 
Paranitrophenylacetylene, 101 
Paranitrophenylalanine, 178 
a-Paranitrophenylchlorolactic acid, 192 
8-Paranitrophenylchlorolactic acid, 192 
Paranitrophenylglycidic acid, 193 
Paranitrophenylnitro-acrylic acid, 238 
Paranitrophenylnitro-ethylene, 35 
Paranitrophenylnitro-ethylene bromide, 
36 
Paranitrophenylnitropropylene, 195 
Paranitrophenylpropiolic acid, 261 
Paranitrostyceric acid, 191 
Paranitrostyrolene, 35 
Para-orthohydroxyuvitiec acid, 136 
Paraphenylenedi-acetic acid, 287 
Paraphenylenedipropionic acid, 387 
Parapropylbenzoic acid, 308 
Parapropylphenol, 158 
Parapropylphenolearboxylic acid, 310 
Parapropylphenylacetic acid, 350 
Parapropylphenyl methyl ether, 159 
Parapropylpropionaldehyde, 312 
Parathymotic acid, 348 
Paratoluylearboxylic acid, 149 
Paratolylmethylketone, 145 
Paratolylparamethylamidoxindol, 89 
Paratolylparamethylimesatin, 89 
Paravinylanisol, 31 
Paraxylene cyanide, 287 
Paraxylenedicarboxylic acid, 287 
Paraxylic acid, 125 
Paraxylylglyoxylic acid, 285 
Paraxylylmethylketone, 285 
Patchouli camphor, 478 
Pentabromethylbenzene, 5 
Pentabromocumene, 154 
Pentamethylbenzene, 343 
Pentamethylbenzenesulphonamide, 344 
Pentamethylbenzenesulphonic chloride, 
344 
Pentamethylphenol, 344 
Pentamethylphenylcarbamine, 345 
Pentamethylphenyl methyl ether, 344 
Pentamethylphenylthiocarbimide, 345 
Pentenylbenzene, 353 
Pentamethylsulphonic acid, 344 
Pentylbenzene, 351 
Pentylbenzenes, the, 351 
Phellandrene, 411, 467 
Phellandrene diamine, 468 
Phellandrene group, 467 
Phellandrene nitrosonitrite, 468 
Phenisobutyl mustard oil, 319 
Phenolisatin, 87 


OO 


INDEX. 


Phenoxycinnamic acid, 235 
Phenylacetaldehyde, 9 
Phenylacetamide, 13 
Phenylacetates, the, 13 
Phenylacetic acid, 10; properties, 12 ; 
halogen substitution products of, 15 
Phenylacetonitril, 14 
Phenylacetorthocarboxylic acid, 150 
Phenylacetosuccinie acid, 388 
Phenylaceturic acid, 14 
Phenylacetylacetone, 357 
Phenylacetyl chloride, 13 
Phenylacetyl compounds, 9 
Phenylacetylene, 100 
Phenylacryl-compounds, 206 
a-Phenylacrylic acid, 233 
B-Phenylacrylic acid, 211 
Phenylalanine, 178 
Phenylallenylamidoxime, 217: 
Phenylallyl alcohol, 203 
Phenylallyl compounds, 203 
Phenylamido-acetic acid, 47 
a-Phenyl-a-amidopropionic acid, 176 
B-Phenyl-a-amidopropionic acid, 178 
a-Phenyl-8-amidopropionic acid, 178 
B-Phenyl-8-amidopropionic acid, 184 
Phenylamylene, 354 
Phenylamylene dibromide, 354 
Phenylamylenglycol, 354 
Phenylangelamide, 366 
Phenylangelic acid, 366 
Phenylazo-indoxyl, 40, 42 
Phenylbromacetic acid, 46 
Phenylbromacetimido-bromide, 14 
Phenyl-a-bromaecrylic acid, 236 
Phenyl-8-bromacrylic acid, 236 
Phenylbromacrylaldehyde, 209 
a-Phenylbromethylene, 33 
B-Phenylbromethylene, 33 
Phenylbromisobutylene, 327 
Phenylbromisobutylene dibromide, 327 
a-Phenylbromolactic acid, 193 
B-Phenylbromolactie acid, 192 
Phenylbromonitro-ethylene, 34 
a-Phenyl-a-bromopropionic acid, 176 
a-Phenyl-8-bromopropionic acid, 178 
B-Phenyl-8-bromopropionic acid, 184 
Phenylbutinedicarboxylic acid, 369, 
393 
Phenylbutinylcarboxylic acid, 369 
Phenylbutinylmethylketone, 369 
Phenyl-a-butylene, 326 
Phenyl-8-butylene, 326 
Phenylbutylene alcohol, 327 
Phenylbutylenes, 326 
Phenylbutylketone, 357 
Phenylbutyrolactone, 321 
Phenylbutyro-orthocarboxylic acid, 363 
Phenylbutyric acid, 320 
Phenylearbostyril, 224 
Phenylearboxysuccinic acid, 366 
Phenylchloracetic acid, 46 
Phenyl-a-chloracrylic acid, 235 
Phenyl-8-chloracrylic acid, 236 


299 


519 
a-Phenylchlorethylene, 32 
B-Phenylchlorethylene, 32 
Phenylehlorohydroxypropionic acid, 


192 
a-Phenylchlorolactic acid, 192 
Phenylchloronitroethylene, 34 
a-Phenyl-a-chloropropionic acid, 176 
a-Phenyl-8-chloropropionic acid, 177 
B-Phenyl-8-chloropropionic acid, 184 
Phenylerotonic acid, 328 
Phenyl-a-crotonic acid, 330 
Phenylcrotonylene, 339 
Phenyldehydrohexone, 392 
Phenyldehydrohexonecarboxylic acid, 

392 
Phenyldibromopropionaldehyde, 209 
a-Phenyldibromopropionic acid, 194 
B-Phenyldibromopropionic acid, 191 
Phenyldibromopropy! cinnamate, 216 
Phenyldichloracetic acid, 70 
Phenyldichloracetonitril, 71 
B-Phenyldichloropropionic acid, 191 
Phenyldihydroxypropionic acids, 190 
Phenylenedi-acetic acids, 286 
a-Phenylethidene chloride, 32 
B-Phenylethidene chloride, 32 
Phenylethy] alcohol, 6 
Phenylethylamine, 7 
Phenylethylene, 26, 28 
Phenylethylpropylene, 354 
Phenylglyceric acid, 190 
Phenylglycerol, 190 
Phenylglycidic acid, 193 
Phenylglycocoll, 47 
Phenylglycol, 29 
Phenylglycolyl-compounds, 43 
Phenylglyoxylic acid, 68 
Phenylhomo-itamalic acid, 387 
Phenylhomoparaconic acid, 387, 388 
Phenylhydrazine-imesatin, 88 
Phenylhydrazineparamethylimesatin, 

90 
Phenylhydroxyacetamide, 47 
Phenylhyaroxyacetic acid, 43 
Phenylhydroxyacetonitril, 49 
Phenylhydroxyacrylic acics, 235 
Phenylhydroxybutyric acids, 321 
Phenylhydroxyethenylamidoxime, 49 
Phenylhydroxyisobutyric acid, 321 
Phenyl-a-hydroxyisocrotonic acid, 330 
Phenylhydroxylpivalic acid, 355 
Phenylhydroxypropionic acids, 175 
a-Phenyl-8-hydroxypropionic acid, 177 
B-Phenpl-8-hydroxypropionic acid, 183 
Phenylhydrozinebenzoylformic acid, 68 
Phenylimesatin, 88 
Phenylindol, 39 
Phenylindolearboxylic acid, 270 
a-Phenyliodolactic acid, 193 
B-Phenyl-B-iodopropionic acid, 184 
Phenylisobutylene, 327 
Phenylisobutyl ketone, 357 
Phenylisobutyramide, 321 
Phenylisobutyric acid, 321 


520 


INDEX. 





Phenylisocrotonic acid, 329 
Phenylisohexylene, 389 
Phenylisohomoparaconic acid, 387, 388 
Phenylisoindol, 64 
Phenylisopropy] alcohol, 160 
Phenylisopropylamine, 160 
Phenylisosuccinic acid, 325 
Phenylitamalic acid, 364 
a-Phenyl-lactic acid, 178 
B-Phenyl-lactic acid, 183 
a-Phenyl-lactonitril, 178 
Phenyl-levulinic acid, 359 
Phenylmandelic acid, 46 
Phenylmethylacrylaldehyde, 328 
Phenylmethylacrylic acid, 328 
Phenylmethylamido-acetic acid, 47 
Phenylmethylfurfuran, 358 
Phenylmethylfurfuric acid, 385 
Phenylmethylpyrrolearboxylic acid, 
385 


Phenylmethyltetramethylene oxide, 358 
a-Phenylnitro-ethylene, 33 
Phenylnitro-ethylene bromide, 34 
Phenylnitro-ethylene chloride, 34 
Phenylnitropropylene, 195 
Phenylparaconic acid, 364 
Phenylparamethylimesatin, 90 
Phenylpenteny! dibromide, 354 
Phenylpentoxylic acid, 351 
Phenylpentylene, 353 
Phenylpropenylacetodibromohydrin, 
190 


Phenylpropenyl compounds, 190 
Phenylpropenyldibromohydrate, 190 
Phenylpropenyl tribromide, 190 
Phenylpropiolic acid, 260 
Phenylpropiolie group, 260 
B-Phenylpropionaldeliyde, 164 
a-Phenylpropionic acid, 162 
B-Phenylpropionic acid, 164 
a-Phenyl-a-propionic acid, 175 
B-Phenyl-a-propionic acid, 178 
B-Phenylpropionitril, 166 
Phenylpropionyl compounds, 162 
Phenylpropy] alcohols, 159 
Phenylpropylamine, 160 
Phenylpropyl cinnamate, 216 
Phenylpropylene, 194 
Phenylpropylene bromide, 195 
Phenylpropylglycolic acid, 354 
Phenylsarcosin, 47 
Phenylsuccinic acid, 324 
Phenylsuccinie anhydride, 325 
Phenylvalerolactonecarboxylic acid,388 
Phenylvinyl bromide, 33 
Phenylvinylchloride, 32 
Phenylvinyl ethyl ether, 32 
Phloretic acid, 170 

Phloretin, 171 

Phloridzin, 171 
Phloroglucinoltricarboxylic acid, 143 
Phlorol, 4 

Phthalidecarboxylic acid, 153 
Phthalidepropionic acid, 362 





Phthalimidylacetic acid, 316 
Phthalmethimidylacetic acid, 317 
Phthalylacetic acid, 316 
Phthalylaceto-acetic acid, 391 
Phthalyldi-acetic acid, 388 
Phthalylmalonic ether, 365 
Phthalylprupionic acid, 363 
Phytosterin, 406 

Phytosteryl acetate, 406 
Phytosteryl alcohol, 406 

Pimaric acid, 480 

Pinene dibromide, 415 

Pinene dichloride, 415 

Pinene, 411 ; group, 412 

Pinene hydrochloride, 415 
Pinene nitrosochloride, 415 
Pinoxime, 415 

Pinyl bromide, 416 

Pinyl chloride, 415 

Pinyl sulphate, 422 
Pinyltrimethylammonium iodide, 415 
Piperhydrolactone, 356 
Piperhydronie acid, 351 

Piperic acid, 370 

Piperoketonic acid, 355 
Piperonal, 370 

Piperonylic acid, 370 

Pipitzahoic acid, 397 

Polychrom, 258 

Polystyrolene, 29 

Polyterpenes, 485 
Polythymoquinone, 298 
Polythymoquinonedioxime, 301 
Polythymoquinonoxime, 300 
Potassium chlorisatate, 78 
Potassium dextropimarate, 481 
Potassium dibromisatate, 81 
Potassium dibromisatin, 80 
Potassium dichlorisatate, 79 
Potassium hydrocinnamate, 165 
Potassium isatinsulphite, 78 
Potassium isatinsulphonate, 83 
Potassium phenylhydroxyacetate, 45 
Prehnitene, 272, 276 
Prehnitenesulphonic acid, 274 
Prehnitic acid, 279, 282 
Prehnomalie acid, 283 

Primary phenylpropyl acetate, 160 
Primary phenylpropyl alcohol, 159 
Primary phenylpropyl chloride, 160 
Primary styrolyl alcohol, 6 
Primary styrolyl chloride, 7 
Propenylbenzene sulphamide, 155 
Propenylbenzoic acid, 314 
Propenylsalicylic acid, 315 
Propioncoumarin, 331 
Propiophenone, 161 
Propylbenzene, 103, 157 
Propylbenzenes, 153 
Propylbenzenesulphonic acid, 158 
Propylbenzoic acids, 304 
Propylene-eugenol, 199 
Propyleugenol, 199 
Propylhydrocarbostyril, 383 


INDEX. 521 


Propylhydroxybenzoic acids, 309 
Propylisopropylbenzene, 382 
Propylorthotoluic acid, 347 
Propyl phenylacetate, 13 
Propyl phenyldibromopropionate, 192 
Propylphenylketone, 320 
Propylpyrogallol, 159 
Propylpyrogallol dimethyl] ether, 159 
Propyltoluene, 287 
Pseudocumene, 103, 105 
Pseudocumenequinol, 116 
Pseudocumenesulphamide, 112 
a-Pseudocumenesulphamide, 113 
B-Pseudocumenesulphamide, 113 
y-Pseudocumenesulphamide, 113 
a-Pseudocumenesul phonic acid, 113 
B-Pseudocumenesulphonic acid, 118, 
274 
y-Pseudocumenesulphonic acid, 
274 
a-Pseudocumenesulphonic chloride, 113 
a-Pseudocumenol, 114 
B-Pseudocumenol, 115 
y-Pseudocumenol, 115 
Pseudocumeny! methyl ether, 114 
a-Pseudocumidine, 118 
B-Pseudocumidine, 120 
y-Pseudocumiaine, 120 
Pseudocumol, 103 
Pseudocumoquinolic acid, 278 
Pseudocumoquinonecarboxylic acid, 278 
Pseudocumyl bromide, 132 
Pseudocumylene alcohol, 132 
Pseudocumylene bromide, 132 
Pseudocumylene compounds, 132 
Pseudocumylhydrazine, 120 
Pseudoisatin, 75 
Pseudo-isatin-a-ethyloxime, 94 
Pseudo-isatin-a-oxime, 93 
Pteleyl chloride, 107 
Pulegiol, 474 
Pyroguaiacin, 484 
Pyromellitic acid, 280, 375 
Pyromellitic anhydride, 281 
Pyromellityl chloride, 281 
Pyro-olivilic acid, 200 


113, 


Q. 


QUERBRACHOL, 401 

Querbrachyl acetate, 401 
Querbrachyl alcohol, 401 
Quinacetophenone, 59 

Quinisatic acid, 229 

Quinisatin, 229 

Quinoline, 169 
Quinonetetracarboxylic ether, 283 


R. 


RESACETOPHENONE, 60 
Retindol, 23 


Retinnyl, 102 
Rosemary, oil of, 417 
Rusa oil, 471 


SAFROL, 200, 201 

Sage, oil of, 416 

Salicylglycolic acid, 55 

Salicyl-lactic acid, 189 

Salviol, 416, 474 

Santalal, 478 

Santalol, 478 

Santalyl acetate, 478 

Schillerstoff, 258 

Scopoletin, 335 

Scopolin, 336 

Secondary styrolylacetate, 8 

Secondary styrolyl alcohol, 8 

Secondary styrolylamine, 9 

Secondary styrolyl bromide, 8 

Secondary styrolyl chloride, 8 

Secondary styrolyl ethyl ether, 8 

Sesquicamphors C,,H,,0, 476 | 

Sesquiterpenes C,; Hos, 476 

Shikimene, 201 

Shikiminic acid, 201 

Shikimino-ki, 201 

Shikomol, 201 

Silver azo-dioxindol, 55 

Silver benzoylacetone, 323 

Silver copaivate, 483 

Silver dextropimarate, 481 

Silver dibromisatin, 80 

Silver dimethylhomophthalate, 362 

Silver dioxindol, 53 

Silver ethylisatate, 85 

Silver ethyl] isatoximate, 92 

Silver hydratropate, 163 

Silver hydrocinnamate, 165 

Silver isatate, 77 

Silver isatoximate, 92 

Silver mellitate, 379 

Silver nitroso-dioxindol, 54 

Silver phenylacetate, 13 

Silver phenylacetylene, 100 

Silver phenylhydroxyacetate, 45 

Silver tyrosine, 182 

Skatol, 264, 269 

Skatolearboxylic acid, 341 

Skatolsulphuric acid, 266 

Sodium borneolcarboxylate, 421 

Sodium bornylate, 421 

Sodium camphophenate, 433 

Sodium camphoroximate, 430 

Sodium cyanocamphophenate, 440 

Sodium dextropimarate, 481 

Sodium diethyl hydroxytrimesate, 142 

Sodium dioxindol, 53 

Sodium ethyl benzoylacetate, 187 

Sodium hydrazine-acetophenonesul- 
phonate, 66 

Sodium isatinsulphonate, 83 


522 


Sodium laurenesulphonate, 347 

Sodium mentholate, 470 

Sodium methindazolsulphonate, 66 

Sodium phenylacetylene, 100 

Stilbous acid, 48 

Strontium cumeneparasulphonate, 155 

Styceric acid, 190 

Stycerol, 190 

Styceroldibromohydrin, 190 

Styceroltribromohydrin, 190 

Styracin, 216 

Styracone, 203 

Styril oxide, 203. 

Styrol, 27 

Styrolene, 26 ; properties, 28 

Styrolene acetate, 30 

Styrolene alcohol, 29 

Styrolene benzoate, 31 

Styrolene bromide, 30 

Styrolene chloride, 30 

Styrolene group, 3 

Styrolene iodide, 30 

Styrolene, substitution products of, 31 

Styrolene thiocyanate, 31 

Styrolyl acetate, 7 

Styrolylamine, 7 

Styrolyl compounds, 6 

Styrone, 203 

Substituted indols, 264 

Substitution products of coumarin, 245 

Substitution products of the dimethyl- 
benzenecarboxylic acids, 126 

Substitution products of dioxindol, 55 

Substitution products of isatoic acid, 97 

a-Sulphamidohemellithic acid, 129 

8-Sulphamidohemellithic acid, 129 

a-Sulphamidomesitylenic acid, 128 

B-Sulphamidomesitylenic acid, 129 

Sulphamidotrimesic acid, 139 

Sulphamidoxylic acid, 129 

Sulphamidoxylidic acid, 136 

Sulphamine-uvitic acid, 135 

Sulphasathyde, 96 

Sulphisathyde, 96 

Sulphisatin, 96 

Sulphocamphylic acid, 449 

Sulpho-isatic acid, 83 

Sulphomesitylenic acid, 128 

Sulpho-uvitic acid, 135 

Sycoceryl acetate, 400 

Sycoceryl alcohol, 400 

Sycoceryl benzoate, 400 

Sylvestrene, 411, 464 

Sylvestrene group, 464 

Sylvestrene tetrabromide, 465 

Sylvestrenylene bromide, 465 

Sylvestrenylene chloride, 465 

Sylvestrenylene iodide, 465 

Sylvic acid, 482 


T. 


TANACETOL, 473 
Tanacetyl alcohol, 473 


INDEX. 


Terebenic acid, 414 

Terebentene, 409, 414 

Terecamphene, 409, 417 

Terpene, 411 

Terpene dihydrochloride, 460 

Terpene monohydrochloride, 415 

Terpenes, 410 

Terpenes and camphors, group of, 408 

Terpilene, 411, 455 

Terpine hydrate, 457 

Terpine hydrochloride, 460 

Terpinene, 411, 466 

Terpinene group, 466 

Terpinene nitrolamine, 467 

Terpinene nitroldimethylamine, 467 

Terpinene nitrolmethylamine, 467 

Terpinene nitrosite, 467 

Terpineol, 461, 462 

Terpinol, 461 

Terpinolene, 411, 465 

Terpinolene group, 465 

Terpinolene tetrabromide, 466 

Tetrabromopiperhydronic acid, 371 

Tetrabromopropylbenzene, 158 

Tetra-ethylbenzene, 394 

Tetra-ethylbenzenesulphamide, 395 

Tetra-ethylbenzenesulphonie acid, 395 

Tetrahydrotrihydroxybenzoic acid, 202 

Tetramethylbenzenes, 273 

a-Tetramethylbenzene, 275 

v-Tetramethylbenzene, 276 

s-Tetramethylbenzene, 273 

s-Tetramethylbenzene or durene, 272 

a-Tetramethylbenzene or isodurene, 27 2 

v-Tetramethylbenzene or prehnitene, 
272 

Tetramethylbenzenecarboxylic 
345 

a-Tetramethylbenzoic acid, 384 

s-Tetramethylbenzoic acid, 384 

Tetramethylphenylcarbamine, 276 

Thiocarvacrol, 297 

Thiocoumarin, 245 

Thiocuminamide, 307 

Thiocymene, 297 

Thio-isatyde, 96 

Thiothymol, 295 

Thymoil, 297 

Thymoilol, 298 

Thymol, 289, 294 

Thymoquinhydrone, 298 

Thymogquinol, 298 

Thymoquinone, 297 

Thymoquinone chlorimide, 300 

Thymoquinonoxime, 300 

Thymotic acid, 347 

Thymotide, 347 

Thymoxycuminic acid, 309 

Thymyl acetate, 295 

Thymylamine, 293 

Thymyl benzoate, 295 

Thymyl ethenyl ether, 295 

Thymyl ethyl carbonate, 295 

Thymyl] ethyl ether, 295 


acid, 


INDEX. 


Thymyl methyl ether, 295 
Thymyl phosphate, 295 
Thymy] silicate, 295 
Toluic acid, 11 
Tolu-isatin, 86 
Tolylacrylic acid, 314 
Tolylbutylene, 353 
Tolylethylene, 147 
Tolylmethylketones, 145 
Tolylpropionic acids, 311 
Tribasic acids, 365 
Tribromamylbenzene, 351 
a-Tribromethylmetaxylene, 284 
s-Tribromethylmetaxylene, 284 
Tribromisatoxime, 93 
Tribromohemellithene, 109 
Tribromolaurene, 346 
Tribromomesitylene, 108 
Tribromomethyldiethylbenzene, 346 
Tribromopseudocumene, 109 
Trichamomillol, 475 
Trichlorocamphor, 434 
Trichloromesitylene, 107 
a-Triethylesculetic acid, 257 
B-Triethylesculetic acid, 257 
s-Triethylbenzene, C,H3(C,H;)3, 381, 
Triethyl benzylmalonorthocarboxylate 
366 
Triethyldaphnetic acid, 255 
Triethylhydrodaphnetic acid, 256 
Trihydroxyacetophenone, 60 
Trihydroxyphenylacrylic acids, 254 
Trihydroxyphenylcrotonic acids, 335 
Trihydroxytrimesic acid, 143 
Trimellithic acid, 139 
Trimesic acid, 138 
a-Trimethylbenzene or pseudocumene, 
103, 105 
s-Trimethylbenzene or mesitylene, 103, 
104 
v-Trimethylbenzene or hemellithene, 
103, 106 
Trimethylbenzenecarboxylic acids, 277 
Trimethylbenzenedicarboxylic acid, 345 
Trimethylbenzenesulphonic acids, 112 
Trimethylbenzenes, 104 
Trimethyldiethylbenzene, 394 
Trimethyldihydroxybenzenes, 116 
Trimethylene-eugenol, 199 


523 


Trimethylhomophthalimide, 151 
Trimethylhydroxybenzenes, 114 
Trimethylindol, 340 
Trinitrocumene, 157 
s-Trinitro-ethylmetaxylene, 284 
Trinitrohemellithene, 111 
Trinitromesitylene, 110 
Trinitromethylethylbenzene, 144 
Trinitropseudocumene, 111 
Triperpene, 475 
Tristyrolylamine, 8 

Trixis pipitzahuac, 398 

Tropic acid, 177 

Turkish oil of geranium, 472 
Turpentine, oil of, 410, 412 
Tyrosine, 179 

Tyrosinesulphonic acid, 183 


ee 


UMBELLIC acid, 252 
Umbelliferon, 253, 254 


. Unsaturated dibasic acids, 391 


Uramidocamphoglucuronic acid, 428 
Uvitic acid, 123, 133 


i 


VERATROYLOARBOXYLIC acid, 72 
Verbena oil, 471 
Volatile metanethol, 197 


WV 


West Indian caoutchouc, 488 


X. 


XYLAMIDE, 125 
Xyletic acid, 131 
Xylic acid, 124 
v-Xylic acid, 126 
a-Xylidic acid, 135 
B-Xylidic acid, 136 
Xylyl chloride, 125 
Xylylethlyketone, 357 


THE END. 





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